Methods and apparatuses for performing encoding and decoding on image

ABSTRACT

Provided is a computer-recordable recording medium having stored thereon a video file including artificial intelligence (AI) encoding data, wherein the AI encoding data includes: image data including encoding information of a low resolution image generated by AI down-scaling a high resolution image; and AI data about AI up-scaling of the low resolution image reconstructed according to the image data, wherein the AI data includes: AI target data indicating whether AI up-scaling is to be applied to at least one frame; and AI supplementary data about up-scaling deep neural network (DNN) information used for AI up-scaling of the at least one frame from among a plurality of pieces of pre-set default DNN configuration information, when AI up-scaling is applied to the at least one frame.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation Application of U.S. patentapplication Ser. No. 16/743,613, filed on Jan. 15, 2020, which is aNational Stage of International Application No. PCT/KR2019/013344, filedOct. 11, 2019, and claims priority from Korean Patent Application10-2019-0076569, filed on Jun. 26, 2019, Korean Patent Application No.10-2019-0041111, filed on Apr. 8, 2019, and Korean Patent ApplicationNo. 10-2018-0125406, filed on Oct. 19, 2018, the disclosures of whichare incorporated herein in their entirety by reference.

TECHNICAL FIELD

The disclosure relates to an image processing field. More particularly,the disclosure relates to methods and apparatuses for encoding anddecoding an image based on Deep Neural Network.

BACKGROUND ART

An image is stored in a recording medium or transmitted via acommunication channel in a form of a bitstream after being encoded via acodec following a certain data compression standard, such as the MovingPicture Expert Group (MPEG) standard.

With the development and supply of hardware capable of reproducing andstoring a high resolution and high quality image, the need for a codeccapable of effectively encoding and decoding the high resolution andhigh quality image has increased.

DESCRIPTION OF EMBODIMENTS Technical Problem

According to an aspect of the present invention, there is provided amethod and apparatus for encoding and decoding an image, which uses adeep neural network (DNN) to encode and decode an image at a low bitrate.

In addition, a computer-readable recording medium recording a programfor executing the image encoding method and the image decoding method ina computer according to an embodiment of the present disclosure isdisclosed.

Solution to Problem

In the disclosure, a computer-recordable recording medium has storedthereon a video file including artificial intelligence (AI) encodingdata, wherein the AI encoding data includes: image data includingencoding information of a low resolution image generated by AIdown-scaling a high resolution image; and AI data about AI up-scaling ofthe low resolution image reconstructed according to the image data,wherein the AI data includes: AI target data indicating whether AIup-scaling is to be applied to at least one frame; and AI supplementarydata about up-scaling deep neural network (DNN) information used for AIup-scaling of the at least one frame from among a plurality of pieces ofpre-set default DNN configuration information, when AI up-scaling isapplied to the at least one frame.

According to another embodiment of the disclosure, a video decodingmethod using artificial intelligence (AI) up-scaling includes: receivinga video file including AI encoding data that includes image data and AIdata about AI up-scaling of the image data; obtaining the AI data of theAI encoding data from a metadata box of the video file and obtaining theimage data of the AI encoding data from a media data box of the videofile; reconstructing a low resolution image of a current frame bydecoding the image data; obtaining up-scaling deep neural network (DNN)information of the current frame from the AI data; and generating a highresolution image corresponding to the low resolution image by AIup-scaling the low resolution image according to the up-scaling DNNinformation of the current frame.

According to another embodiment of the disclosure, a video encodingmethod using an artificial intelligence (AI) down-scaling includes:determining down-scaling deep neural network (DNN) information for AIdown-scaling a high resolution image of a current frame to a lowresolution image; generating the low resolution image of the currentframe by AI down-scaling the high resolution image of the current frame,according to the down-scaling DNN information; generating AI data aboutup-scaling DNN information corresponding to the down-scaling DNNinformation, the up-scaling DNN information used to AI up-scale the lowresolution image of the current frame; obtaining image data by encodingthe low resolution image of the current frame; generating AI encodingdata including the image data and the AI data; and outputting a videofile including media data box in which the image data of the AI encodingdata is embedded and a metadata box in which the AI data of the AIencoding data is embedded.

According to another embodiment of the disclosure, a video decodingapparatus performing a video decoding method using artificialintelligence (AI) up-scaling is provided. The video decoding apparatusincludes: a communicator configured to receive a video file including AIencoding data that includes image data and AI data about AI up-scalingof the image data; a parser configured to obtain the AI data of the AIencoding data from a metadata box of the video file and obtain the imagedata of the AI encoding data from a media data box of the video file; afirst decoder configured to reconstruct a low resolution image of acurrent frame by decoding the image data; and an AI up-scaler configuredto obtain up-scaling deep neural network (DNN) information of thecurrent frame from the AI data, and generate a high resolution imagecorresponding to the low resolution image by AI up-scaling the lowresolution image according to the up-scaling DNN information of thecurrent frame.

According to another embodiment of the disclosure, a video encodingapparatus performing a video encoding method using artificialintelligence (AI) down-scaling is provided. The video encoding apparatusincludes: an AI down-scaler configured to determine down-scaling deepneural network (DNN) information for AI down-scaling a high resolutionimage of a current frame to a low resolution image, generate the lowresolution image of the current frame by AI down-scaling the highresolution image of the current frame, and generate AI data used to AIup-scale the low resolution image of the current frame; a first encoderconfigured to determine image data by encoding the low resolution imageof the current frame; a data processor configured to determine AIencoding data including the image data and the AI data; and acommunicator configured to output a video file including a media databox in which the image data of the AI encoding data is embedded and ametadata box in which the AI data of the AI encoding data is embedded.

The technical problems of the disclosure are not limited to theaforementioned technical features, and other unstated technical problemsmay be inferred from embodiments below.

Advantageous Effects of Disclosure

According to artificial intelligence (AI) encoding and AI decodingmethods and apparatuses according to embodiments, an image may beprocessed with a low bitrate via AI-based image encoding and decoding.

BRIEF DESCRIPTION OF DRAWINGS

A brief description of each drawing is provided to more fully understandthe drawing recited in the present specification.

FIG. 1 is a diagram for describing an artificial intelligence (AI)encoding process and an AI decoding process, according to an embodiment.

FIG. 2 is a block diagram of a configuration of an AI decoding apparatusaccording to an embodiment.

FIG. 3 is a diagram showing a second deep neural network (DNN) forperforming AI up-scaling on a second image.

FIG. 4 is a diagram for describing a convolution operation by aconvolution layer.

FIG. 5 is a table showing a mapping relationship between several piecesof image-related information and several pieces of DNN settinginformation.

FIG. 6 is a diagram showing a second image including a plurality offrames.

FIG. 7 is a block diagram of a configuration of an AI encoding apparatusaccording to an embodiment.

FIG. 8 is a diagram showing a first DNN for performing AI down-scalingon an original image.

FIG. 9 is a diagram for describing a method of training a first DNN anda second DNN.

FIG. 10 is a diagram for describing a training process of a first DNNand a second DNN by a training apparatus.

FIG. 11 is a diagram of an apparatus for performing AI down-scaling onan original image and an apparatus for performing AI up-scaling on asecond image.

FIG. 12 is a diagram for describing a corresponding relationship betweenimage data and AI data, together with structures of the image data andAI data.

FIG. 13A is a diagram for describing a flow of data in an AI decodingapparatus, when AI data is embedded in image data.

FIG. 13B is a diagram for describing a flow of data in an AI decodingapparatus, when AI data and image data are separated and included in twofiles.

FIG. 14 illustrates an example of AI encoding data when AI data andimage data are separated in a single file.

FIG. 15A illustrates an example of AI encoding data when AI data isembedded in image data in a single file.

FIG. 15B illustrates an example of AI encoding data when AI data isembedded in image data in a single file.

FIG. 15C illustrates an example of AI encoding data when partial AI datais embedded in image data and remaining AI data is separated from theimage data in a single file.

FIG. 16 illustrates an example of AI encoding data split in videosegment units when AI data and image data are separated as in FIG. 14.

FIG. 17 illustrates an example of AI data and image data separated andtransmitted in two files.

FIG. 18A illustrates an example of a data structure applicable to videoAI data described in FIGS. 14 through 17.

FIG. 18B illustrates an example of a data structure applicable to videosegment AI data described in FIG. 16 or frame group AI data of FIGS. 14,15A to 15C, and 17.

FIG. 19 illustrates a syntax table in which the data structure of FIG.18A is implemented.

FIG. 20 illustrates an example of a data structure applicable to framegroup AI data or frame AI data described in FIGS. 14 through 17.

FIG. 21 illustrates a syntax table in which the data structure of FIG.20 is implemented.

FIG. 22 is a flowchart of an image decoding method according to an AIdecoder, according to the disclosure.

FIG. 23 is a flowchart of an image encoding method according to an AIencoder, according to the disclosure.

FIG. 24 is a block diagram showing a configuration of an image decodingapparatus, according to the disclosure.

FIG. 25 is a block diagram showing a configuration of an image encodingapparatus, according to the disclosure.

BEST MODE

In the disclosure, a computer-recordable recording medium has storedthereon a video file including artificial intelligence (AI) encodingdata, wherein the AI encoding data includes: image data includingencoding information of a low resolution image generated by AIdown-scaling a high resolution image; and AI data about AI up-scaling ofthe low resolution image reconstructed according to the image data,wherein the AI data includes: AI target data indicating whether AIup-scaling is to be applied to at least one frame; and AI supplementarydata about up-scaling deep neural network (DNN) information used for AIup-scaling of the at least one frame from among a plurality of pieces ofpre-set default DNN configuration information, when AI up-scaling isapplied to the at least one frame.

MODE OF DISCLOSURE

As the disclosure allows for various changes and numerous examples,particular embodiments will be illustrated in the drawings and describedin detail in the written description. However, this is not intended tolimit the disclosure to particular modes of practice, and it will beunderstood that all changes, equivalents, and substitutes that do notdepart from the spirit and technical scope of the disclosure areencompassed in the disclosure.

In the description of embodiments, certain detailed explanations ofrelated art are omitted when it is deemed that they may unnecessarilyobscure the essence of the disclosure. Also, numbers (for example, afirst, a second, and the like) used in the description of thespecification are merely identifier codes for distinguishing one elementfrom another.

Also, in the present specification, it will be understood that whenelements are “connected” or “coupled” to each other, the elements may bedirectly connected or coupled to each other, but may alternatively beconnected or coupled to each other with an intervening elementtherebetween, unless specified otherwise.

In the present specification, regarding an element represented as a“unit” or a “module”, two or more elements may be combined into oneelement or one element may be divided into two or more elementsaccording to subdivided functions. In addition, each element describedhereinafter may additionally perform some or all of functions performedby another element, in addition to main functions of itself, and some ofthe main functions of each element may be performed entirely by anothercomponent.

Also, in the present specification, an ‘image’ or a ‘picture’ may denotea still image, a moving image including a plurality of consecutive stillimages (or frames), or a video.

Also, in the present specification, a deep neural network (DNN) is arepresentative example of an artificial neural network model simulatingbrain nerves, and is not limited to an artificial neural network modelusing a specific algorithm.

Also, in the present specification, a ‘parameter’ is a value used in anoperation process of each layer forming a neural network, and forexample, may include a weight used when an input value is applied to acertain operation expression. Here, the parameter may be expressed in amatrix form. The parameter is a value set as a result of training, andmay be updated through separate training data when necessary.

Also, in the present specification, a ‘first DNN’ indicates a DNN usedfor artificial intelligence (AI) down-scaling an image, and a ‘secondDNN’ indicates a DNN used for AI up-scaling an image.

Also, in the present specification, ‘DNN setting information’ includesinformation related to an element constituting a DNN. ‘DNN settinginformation’ includes the parameter described above as informationrelated to the element constituting the DNN. The first DNN or the secondDNN may be set by using the DNN setting information.

Also, in the present specification, an ‘original image’ denotes an imageto be an object of AI encoding, and a ‘first image’ denotes an imageobtained as a result of performing AI down-scaling on the original imageduring an AI encoding process. Also, a ‘second image’ denotes an imageobtained via first decoding during an AI decoding process, and a ‘thirdimage’ denotes an image obtained by AI up-scaling the second imageduring the AI decoding process.

Also, in the present specification, ‘AI down-scale’ denotes a process ofdecreasing resolution of an image based on AI, and ‘first encoding’denotes an encoding process according to an image compression methodbased on frequency transformation. Also, ‘first decoding’ denotes adecoding process according to an image reconstruction method based onfrequency transformation, and ‘AI up-scale’ denotes a process ofincreasing resolution of an image based on AI.

FIG. 1 is a diagram for describing an AI encoding process and an AIdecoding process, according to an embodiment.

As described above, when resolution of an image remarkably increases,the throughput of information for encoding and decoding the image isincreased, and accordingly, a method for improving efficiency ofencoding and decoding of an image is required.

As shown in FIG. 1, according to an embodiment of the disclosure, afirst image 115 is obtained by performing AI down-scaling 110 on anoriginal image 105 having high resolution. Then, first encoding 120 andfirst decoding 130 are performed on the first image 115 havingrelatively low resolution, and thus a bitrate may be largely reducedcompared to when the first encoding and the first decoding are performedon the original image 105.

In particular, in FIG. 1, the first image 115 is obtained by performingthe AI down-scaling 110 on the original image 105 and the first encoding120 is performed on the first image 115 during the AI encoding process,according to an embodiment. During the AI decoding process, AI encodingdata including AI data and image data, which are obtained as a result ofAI encoding is received, a second image 135 is obtained via the firstdecoding 130, and a third image 145 is obtained by performing AIup-scaling 140 on the second image 135.

Referring to the AI encoding process in detail, when the original image105 is received, the AI down-scaling 110 is performed on the originalimage 105 to obtain the first image 115 of certain resolution or certainquality. Here, the AI down-scaling 110 is performed based on AI, and AIfor the AI down-scaling 110 needs to be trained jointly with AI for theAI up-scaling 140 of the second image 135. This is because, when the AIfor the AI down-scaling 110 and the AI for the AI up-scaling 140 areseparately trained, a difference between the original image 105 which isan object of AI encoding and the third image 145 reconstructed throughAI decoding is increased.

In an embodiment of the disclosure, the AI data may be used to maintainsuch a joint relationship during the AI encoding process and the AIdecoding process. Accordingly, the AI data obtained through the AIencoding process may include information indicating an up-scalingtarget, and during the AI decoding process, the AI up-scaling 140 isperformed on the second image 135 according to the up-scaling targetverified based on the AI data.

The AI for the AI down-scaling 110 and the AI for the AI up-scaling 140may be embodied as a DNN. As will be described later with reference toFIG. 9, because a first DNN and a second DNN are jointly trained bysharing loss information under a certain target, an AI encodingapparatus may provide target information used during joint training ofthe first DNN and the second DNN to an AI decoding apparatus, and the AIdecoding apparatus may perform the AI up-scaling 140 on the second image135 to target resolution based on the provided target information.

Regarding the first encoding 120 and the first decoding 130 of FIG. 1,information amount of the first image 115 obtained by performing AIdown-scaling 110 on the original image 105 may be reduced through thefirst encoding 120. The first encoding 120 may include a process ofgenerating prediction data by predicting the first image 115, a processof generating residual data corresponding to a difference between thefirst image 115 and the prediction data, a process of transforming theresidual data of a spatial domain component to a frequency domaincomponent, a process of quantizing the residual data transformed to thefrequency domain component, and a process of entropy-encoding thequantized residual data. Such first encoding 120 may be performed viaone of image compression methods using frequency transformation, such asMPEG-2, H.264 Advanced Video Coding (AVC), MPEG-4, High Efficiency VideoCoding (HEVC), VC-1, VP8, VP9, and AOMedia Video 1 (AV1).

The second image 135 corresponding to the first image 115 may bereconstructed by performing the first decoding 130 on the image data.The first decoding 130 may include a process of generating the quantizedresidual data by entropy-decoding the image data, a process ofinverse-quantizing the quantized residual data, a process oftransforming the residual data of the frequency domain component to thespatial domain component, a process of generating the prediction data,and a process of reconstructing the second image 135 by using theprediction data and the residual data. Such first decoding 130 may beperformed via an image reconstruction method corresponding to one ofimage compression methods using frequency transformation, such asMPEG-2, H.264 AVC, MPEG-4, HEVC, VC-1, VP8, VP9, and AV1, which is usedin the first encoding 120.

The AI encoding data obtained through the AI encoding process mayinclude the image data obtained as a result of performing the firstencoding 120 on the first image 115, and the AI data related to the AIdown-scaling 110 of the original image 105. The image data may be usedduring the first decoding 130 and the AI data may be used during the AIup-scaling 140.

The image data may be transmitted in a form of a bitstream. The imagedata may include data obtained based on pixel values in the first image115, for example, residual data that is a difference between the firstimage 115 and prediction data of the first image 115. Also, the imagedata includes information used during the first encoding 120 performedon the first image 115. For example, the image data may includeprediction mode information, motion information, and information relatedto quantization parameter used during the first encoding 120. The imagedata may be generated according to a rule, for example, according to asyntax, of an image compression method used during the first encoding120, among MPEG-2, H.264 AVC, MPEG-4, HEVC, VC-1, VP8, VP9, and AV1.

The AI data is used in the AI up-scaling 140 based on the second DNN. Asdescribed above, because the first DNN and the second DNN are jointlytrained, the AI data includes information enabling the AI up-scaling 140to be performed accurately on the second image 135 through the secondDNN. During the AI decoding process, the AI up-scaling 140 may beperformed on the second image 135 to have targeted resolution and/orquality, based on the AI data.

The AI data may be transmitted together with the image data in a form ofa bitstream. Alternatively, according to an embodiment, the AI data maybe transmitted separately from the image data, in a form of a frame or apacket. The AI data and the image data obtained as a result of the AIencoding may be transmitted through the same network or throughdifferent networks.

FIG. 2 is a block diagram of a configuration of an AI decoding apparatus100 according to an embodiment.

Referring to FIG. 2, the AI decoding apparatus 200 according to anembodiment may include a receiver 210 and an AI decoder 230. Thereceiver 210 may include a communicator 212, a parser 214, and anoutputter 216. The AI decoder 230 may include a first decoder 232 and anAI up-scaler 234.

The receiver 210 receives and parses AI encoding data obtained as aresult of AI encoding, and distinguishably outputs image data and AIdata to the AI decoder 230.

In particular, the communicator 212 receives the AI encoding dataobtained as the result of AI encoding through a network. The AI encodingdata obtained as the result of performing AI encoding includes the imagedata and the AI data. The image data and the AI data may be receivedthrough a same type of network or different types of networks.

The parser 214 receives the AI encoding data received through thecommunicator 212 and parses the AI encoding data to distinguish theimage data and the AI data. For example, the parser 214 may distinguishthe image data and the AI data by reading a header of data obtained fromthe communicator 212. According to an embodiment, the parser 214distinguishably transmits the image data and the AI data to theoutputter 216 via the header of the data received through thecommunicator 212, and the outputter 216 transmits the distinguishedimage data and AI data respectively to the first decoder 232 and the AIup-scaler 234. At this time, it may be verified that the image dataincluded in the AI encoding data is image data generated via a certaincodec (for example, MPEG-2, H.264 AVC, MPEG-4, HEVC, VC-1, VP8, VP9, orAV1). In this case, corresponding information may be transmitted to thefirst decoder 232 through the outputter 216 such that the image data isprocessed via the verified codec.

According to an embodiment, the AI encoding data parsed by the parser214 may be obtained from a data storage medium including a magneticmedium such as a hard disk, a floppy disk, or a magnetic tape, anoptical recording medium such as CD-ROM or DVD, or a magneto-opticalmedium such as a floptical disk.

The first decoder 232 reconstructs the second image 135 corresponding tothe first image 115, based on the image data. The second image 135obtained by the first decoder 232 is provided to the AI up-scaler 234.According to an embodiment, first decoding related information, such asprediction mode information, motion information, quantization parameterinformation, or the like included in the image data may be furtherprovided to the AI up-scaler 234.

Upon receiving the AI data, the AI up-scaler 234 performs AI up-scalingon the second image 135, based on the AI data. According to anembodiment, the AI up-scaling may be performed by further using thefirst decoding related information, such as the prediction modeinformation, the quantization parameter information, or the likeincluded in the image data.

The receiver 210 and the AI decoder 230 according to an embodiment aredescribed as individual devices, but may be implemented through oneprocessor. In this case, the receiver 210 and the AI decoder 230 may beimplemented through an dedicated processor or through a combination ofsoftware and general-purpose processor such as application processor(AP), central processing unit (CPU) or graphic processing unit (GPU).The dedicated processor may be implemented by including a memory forimplementing an embodiment of the disclosure or by including a memoryprocessor for using an external memory.

Also, the receiver 210 and the AI decoder 230 may be configured by aplurality of processors. In this case, the receiver 210 and the AIdecoder 230 may be implemented through a combination of dedicatedprocessors or through a combination of software and general-purposeprocessors such as AP, CPU or GPU. Similarly, the AI up-scaler 234 andthe first decoder 232 may be implemented by different processors.

The AI data provided to the AI up-scaler 234 includes informationenabling the second image 135 to be processed via AI up-scaling. Here,an up-scaling target should correspond to down-scaling of a first DNN.Accordingly, the AI data includes information for verifying adown-scaling target of the first DNN.

Examples of the information included in the AI data include differenceinformation between resolution of the original image 105 and resolutionof the first image 115, and information related to the first image 115.

The difference information may be expressed as information about aresolution conversion degree of the first image 115 compared to theoriginal image 105 (for example, resolution conversion rateinformation). Also, because the resolution of the first image 115 isverified through the resolution of the reconstructed second image 135and the resolution conversion degree is verified accordingly, thedifference information may be expressed only as resolution informationof the original image 105. Here, the resolution information may beexpressed as vertical/horizontal sizes or as a ratio (16:9, 4:3, or thelike) and a size of one axis. Also, when there is pre-set resolutioninformation, the resolution information may be expressed in a form of anindex or flag.

The information related to the first image 115 may include informationabout at least one of a bitrate of the image data obtained as the resultof performing first encoding on the first image 115 or a codec type usedduring the first encoding of the first image 115.

The AI up-scaler 234 may determine the up-scaling target of the secondimage 135, based on at least one of the difference information or theinformation related to the first image 115, which are included in the AIdata. The up-scaling target may indicate, for example, to what degreeresolution is to be up-scaled for the second image 135. When theup-scaling target is determined, the AI up-scaler 234 performs AIup-scaling on the second image 135 through a second DNN to obtain thethird image 145 corresponding to the up-scaling target.

Before describing a method, performed by the AI up-scaler 234, ofperforming AI up-scaling on the second image 135 according to theup-scaling target, an AI up-scaling process through the second DNN willbe described with reference to FIGS. 3 and 4.

FIG. 3 is a diagram showing a second DNN 300 for performing AIup-scaling on the second image 135, and FIG. 4 is a diagram fordescribing a convolution operation in a first convolution layer 310 ofFIG. 3.

As shown in FIG. 3, the second image 135 is input to the firstconvolution layer 310. 3×3×4 indicated in the first convolution layer310 shown in FIG. 3 indicates that a convolution process is performed onone input image by using four filter kernels having a size of 3×3. Fourfeature maps are generated by the four filter kernels as a result of theconvolution process. Each feature map indicates inherent characteristicsof the second image 135. For example, each feature map may represent avertical direction characteristic, a horizontal directioncharacteristic, or an edge characteristic, etc of the second image 135.

A convolution operation in the first convolution layer 310 will bedescribed in detail with reference to FIG. 4.

One feature map 450 may be generated through multiplication and additionbetween parameters of a filter kernel 430 having a a size of 3×3 used inthe first convolution layer 310 and corresponding pixel values in thesecond image 135. Because four filter kernels are used in the firstconvolution layer 310, four feature maps may be generated through theconvolution operation using the four filter kernels.

I1 through I49 indicated in the second image 135 in FIG. 4 indicatepixels in the second image 135, and F1 through F9 indicated in thefilter kernel 430 indicate parameters of the filter kernel 430. Also, M1through M9 indicated in the feature map 450 indicate samples of thefeature map 450.

In FIG. 4, the second image 135 includes 49 pixels, but the number ofpixels is only an example and when the second image 135 has a resolutionof 4 K, the second image 135 may include, for example, 3840×2160 pixels.

During a convolution operation process, pixel values of I1, I2, I3, I8,I9, I10, I15, I16, and I17 of the second image 135 and F1 through F9 ofthe filter kernels 430 are respectively multiplied, and a value ofcombination (for example, addition) of result values of themultiplication may be assigned as a value of M1 of the feature map 450.When a stride of the convolution operation is 2, pixel values of I3, I4,I5, I10, I11, I12, I17, I18, and I19 of the second image 135 and F1through F9 of the filter kernels 430 are respectively multiplied, andthe value of the combination of the result values of the multiplicationmay be assigned as a value of M2 of the feature map 450.

While the filter kernel 430 moves along the stride to the last pixel ofthe second image 135, the convolution operation is performed between thepixel values in the second image 135 and the parameters of the filterkernel 430, and thus the feature map 450 having a certain size may begenerated.

According to the present disclosure, values of parameters of a secondDNN, for example, values of parameters of a filter kernel used inconvolution layers of the second DNN (for example, F1 through F9 of thefilter kernel 430), may be optimized through joint training of a firstDNN and the second DNN. As described above, the AI up-scaler 234 maydetermine an up-scaling target corresponding to a down-scaling target ofthe first DNN based on AI data, and determine parameters correspondingto the determined up-scaling target as the parameters of the filterkernel used in the convolution layers of the second DNN.

Convolution layers included in the first DNN and the second DNN mayperform processes according to the convolution operation processdescribed with reference to FIG. 4, but the convolution operationprocess described with reference to FIG. 4 is only an example and is notlimited thereto.

Referring back to FIG. 3, the feature maps output from the firstconvolution layer 310 may be input to a first activation layer 320.

The first activation layer 320 may assign a non-linear feature to eachfeature map. The first activation layer 320 may include a sigmoidfunction, a Tan h function, a rectified linear unit (ReLU) function, orthe like, but is not limited thereto.

The first activation layer 320 assigning the non-linear featureindicates that at least one sample value of the feature map, which is anoutput of the first convolution layer 310, is changed. Here, the changeis performed by applying the non-linear feature.

The first activation layer 320 determines whether to transmit samplevalues of the feature maps output from the first convolution layer 310to the second convolution layer 330. For example, some of the samplevalues of the feature maps are activated by the first activation layer320 and transmitted to the second convolution layer 330, and some of thesample values are deactivated by the first activation layer 320 and nottransmitted to the second convolution layer 330. The intrinsiccharacteristics of the second image 135 represented by the feature mapsare emphasized by the first activation layer 320.

Feature maps 325 output from the first activation layer 320 are input tothe second convolution layer 330. One of the feature maps 325 shown inFIG. 3 is a result of processing the feature map 450 described withreference to FIG. 4 in the first activation layer 320.

3×3×4 indicated in the second convolution layer 330 indicates that aconvolution process is performed on the feature maps 325 by using fourfilter kernels having a size of 3×3. An output of the second convolutionlayer 330 is input to a second activation layer 340. The secondactivation layer 340 may assign a non-linear feature to input data.

Feature maps 345 output from the second activation layer 340 are inputto a third convolution layer 350. 3×3×1 indicated in the thirdconvolution layer 350 shown in FIG. 3 indicates that a convolutionprocess is performed to generate one output image by using one filterkernel having a size of 3×3. The third convolution layer 350 is a layerfor outputting a final image and generates one output by using onefilter kernel. According to an embodiment of the disclosure, the thirdconvolution layer 350 may output the third image 145 as a result of aconvolution operation.

There may be a plurality of pieces of DNN setting information indicatingthe numbers of filter kernels of the first, second, and thirdconvolution layers 310, 330, and 350 of the second DNN 300, a parameterof filter kernels of the first, second, and third convolution layers310, 330, and 350 of the second DNN 300, and the like, as will bedescribed later, and the plurality of pieces of DNN setting informationshould be connected to a plurality of pieces of DNN setting informationof a first DNN. The connection between the plurality of pieces of DNNsetting information of the second DNN and the plurality of pieces of DNNsetting information of the first DNN may be realized via joint trainingof the first DNN and the second DNN.

In FIG. 3, the second DNN 300 includes three convolution layers (thefirst, second, and third convolution layers 310, 330, and 350) and twoactivation layers (the first and second activation layers 320 and 340),but this is only an example, and the numbers of convolution layers andactivation layers may vary according to an embodiment. Also, accordingto an embodiment, the second DNN 300 may be implemented as a recurrentneural network (RNN). In this case, a convolutional neural network (CNN)structure of the second DNN 300 according to an embodiment of thedisclosure is changed to an RNN structure.

According to an embodiment, the AI up-scaler 234 may include at leastone arithmetic logic unit (ALU) for the convolution operation and theoperation of the activation layer described above. The ALU may beimplemented as a processor. For the convolution operation, the ALU mayinclude a multiplier that performs multiplication between sample valuesof the second image 135 or the feature map output from previous layerand sample values of the filter kernel, and an adder that adds resultvalues of the multiplication. Also, for the operation of the activationlayer, the ALU may include a multiplier that multiplies an input samplevalue by a weight used in a pre-determined sigmoid function, a Tan hfunction, or an ReLU function, and a comparator that compares amultiplication result and a certain value to determine whether totransmit the input sample value to a next layer.

Hereinafter, a method, performed by the AI up-scaler 234, of performingthe AI up-scaling on the second image 135 according to the up-scalingtarget will be described.

According to an embodiment, the AI up-scaler 234 may store a pluralityof pieces of DNN setting information settable in a second DNN.

Here, the DNN setting information may include information about at leastone of the number of convolution layers included in the second DNN, thenumber of filter kernels for each convolution layer, or a parameter ofeach filter kernel. The plurality of pieces of DNN setting informationmay respectively correspond to various up-scaling targets, and thesecond DNN may operate based on DNN setting information corresponding toa certain up-scaling target. The second DNN may have differentstructures based on the DNN setting information. For example, the secondDNN may include three convolution layers based on any piece of DNNsetting information, and may include four convolution layers based onanother piece of DNN setting information.

According to an embodiment, the DNN setting information may only includea parameter of a filter kernel used in the second DNN. In this case, thestructure of the second DNN does not change, but only the parameter ofthe internal filter kernel may change based on the DNN settinginformation.

The AI up-scaler 234 may obtain the DNN setting information forperforming AI up-scaling on the second image 135, among the plurality ofpieces of DNN setting information. Each of the plurality of pieces ofDNN setting information used at this time is information for obtainingthe third image 145 of pre-determined resolution and/or pre-determinedquality, and is trained jointly with a first DNN.

For example, one piece of DNN setting information among the plurality ofpieces of DNN setting information may include information for obtainingthe third image 145 of resolution twice higher than resolution of thesecond image 135, for example, the third image 145 of 4 K (4096×2160)twice higher than 2 K (2048×1080) of the second image 135, and anotherpiece of DNN setting information may include information for obtainingthe third image 145 of resolution four times higher than the resolutionof the second image 135, for example, the third image 145 of 8 K(8192×4320) four times higher than 2 K (2048×1080) of the second image135.

Each of the plurality of pieces of DNN setting information is obtainedjointly with DNN setting information of the first DNN of an AI encodingapparatus 600 of FIG. 6, and the AI up-scaler 234 obtains one piece ofDNN setting information among the plurality of pieces of DNN settinginformation according to an enlargement ratio corresponding to areduction ratio of the DNN setting information of the first DNN. In thisregard, the AI up-scaler 234 may verify information of the first DNN. Inorder for the AI up-scaler 234 to verify the information of the firstDNN, the AI decoding apparatus 200 according to an embodiment receivesAI data including the information of the first DNN from the AI encodingapparatus 600.

In other words, the AI up-scaler 234 may verify information targeted byDNN setting information of the first DNN used to obtain the first image115 and obtain the DNN setting information of the second DNN trainedjointly with the DNN setting information of the first DNN, by usinginformation received from the AI encoding apparatus 600.

When DNN setting information for performing the AI up-scaling on thesecond image 135 is obtained from among the plurality of pieces of DNNsetting information, input data may be processed based on the second DNNoperating according to the obtained DNN setting information.

For example, when any one piece of DNN setting information is obtained,the number of filter kernels included in each of the first, second, andthird convolution layers 310, 330, and 350 of the second DNN 300 of FIG.3, and the parameters of the filter kernels are set to values includedin the obtained DNN setting information.

In particular, parameters of a filter kernel of 3×3 used in any oneconvolution layer of the second DNN of FIG. 4 are set to {1, 1, 1, 1, 1,1, 1, 1, 1}, and when DNN setting information is changed afterwards, theparameters are replaced by {2, 2, 2, 2, 2, 2, 2, 2, 2} that areparameters included in the changed DNN setting information.

The AI up-scaler 234 may obtain the DNN setting information for AIup-scaling from among the plurality of pieces of DNN settinginformation, based on information included in the AI data, and the AIdata used to obtain the DNN setting information will now be described.

According to an embodiment, the AI up-scaler 234 may obtain the DNNsetting information for AI up-scaling from among the plurality of piecesof DNN setting information, based on difference information included inthe AI data. For example, when it is verified that the resolution (forexample, 4 K (4096×2160)) of the original image 105 is twice higher thanthe resolution (for example, 2 K (2048×1080)) of the first image 115,based on the difference information, the AI up-scaler 234 may obtain theDNN setting information for increasing the resolution of the secondimage 135 two times.

According to another embodiment, the AI up-scaler 234 may obtain the DNNsetting information for AI up-scaling the second image 135 from amongthe plurality of pieces of DNN setting information, based on informationrelated to the first image 115 included in the AI data. The AI up-scaler234 may pre-determine a mapping relationship between image-relatedinformation and DNN setting information, and obtain the DNN settinginformation mapped to the information related to the first image 115.

FIG. 5 is a table showing a mapping relationship between several piecesof image-related information and several pieces of DNN settinginformation.

Through an embodiment according to FIG. 5, it will be determined that AIencoding and AI decoding processes according to an embodiment of thedisclosure do not only consider a change of resolution. As shown in FIG.5, DNN setting information may be selected considering resolution, suchas standard definition (SD), high definition (HD), or full HD, abitrate, such as 10 Mbps, 15 Mbps, or 20 Mbps, and codec information,such as AV1, H.264, or HEVC, individually or collectively. For suchconsideration of the resolution, the bitrate and the codec information,training in consideration of each element should be jointly performedwith encoding and decoding processes during an AI training process (seeFIG. 9).

Accordingly, when a plurality of pieces of DNN setting information areprovided based on image-related information including a codec type,resolution of an image, and the like, as shown in FIG. 5 according totraining, the DNN setting information for AI up-scaling the second image135 may be obtained based on the information related to the first image115 received during the AI decoding process.

In other words, the AI up-scaler 234 is capable of using DNN settinginformation according to image-related information by matching theimage-related information at the left of a table of FIG. 5 and the DNNsetting information at the right of the table.

As shown in FIG. 5, when it is verified, from the information related tothe first image 115, that the resolution of the first image 115 is SD, abitrate of image data obtained as a result of performing first encodingon the first image 115 is 10 Mbps, and the first encoding is performedon the first image 115 via AV1 codec, the AI up-scaler 234 may use A DNNsetting information among the plurality of pieces of DNN settinginformation.

Also, when it is verified, from the information related to the firstimage 115, that the resolution of the first image 115 is HD, the bitrateof the image data obtained as the result of performing the firstencoding is 15 Mbps, and the first encoding is performed via H.264codec, the AI up-scaler 234 may use B DNN setting information among theplurality of pieces of DNN setting information.

Also, when it is verified, from the information related to the firstimage 115, that the resolution of the first image 115 is full HD, thebitrate of the image data obtained as the result of performing the firstencoding is 20 Mbps, and the first encoding is performed via HEVC codec,the AI up-scaler 234 may use C DNN setting information among theplurality of pieces of DNN setting information, and when it is verifiedthat the resolution of the first image 115 is full HD, the bitrate ofthe image data obtained as the result of performing the first encodingis 15 Mbps, and the first encoding is performed via HEVC codec, the AIup-scaler 234 may use D DNN setting information among the plurality ofpieces of DNN setting information. One of the C DNN setting informationand the D DNN setting information is selected based on whether thebitrate of the image data obtained as the result of performing the firstencoding on the first image 115 is 20 Mbps or 15 Mbps. The differentbitrates of the image data, obtained when the first encoding isperformed on the first image 115 of the same resolution via the samecodec, indicates different qualities of reconstructed images.Accordingly, a first DNN and a second DNN may be jointly trained basedon certain image quality, and accordingly, the AI up-scaler 234 mayobtain DNN setting information according to a bitrate of image dataindicating the quality of the second image 135.

According to another embodiment, the AI up-scaler 234 may obtain the DNNsetting information for performing AI up-scaling on the second image 135from among the plurality of pieces of DNN setting informationconsidering both information (prediction mode information, motioninformation, quantization parameter information, and the like) providedfrom the first decoder 232 and the information related to the firstimage 115 included in the AI data. For example, the AI up-scaler 234 mayreceive quantization parameter information used during a first encodingprocess of the first image 115 from the first decoder 232, verify abitrate of image data obtained as an encoding result of the first image115 from AI data, and obtain DNN setting information corresponding tothe quantization parameter information and the bitrate. Even when thebitrates are the same, the quality of reconstructed images may varyaccording to the complexity of an image. A bitrate is a valuerepresenting the entire first image 115 on which first encoding isperformed, and the quality of each frame may vary even within the firstimage 115. Accordingly, DNN setting information more suitable for thesecond image 135 may be obtained when prediction mode information,motion information, and/or a quantization parameter obtainable for eachframe from the first decoder 232 are/is considered together, compared towhen only the AI data is used.

Also, according to an embodiment, the AI data may include an identifierof mutually agreed DNN setting information. An identifier of DNN settinginformation is information for distinguishing a pair of pieces of DNNsetting information jointly trained between the first DNN and the secondDNN, such that AI up-scaling is performed on the second image 135 to theup-scaling target corresponding to the down-scaling target of the firstDNN. The AI up-scaler 234 may perform AI up-scaling on the second image135 by using the DNN setting information corresponding to the identifierof the DNN setting information, after obtaining the identifier of theDNN setting information included in the AI data. For example,identifiers indicating each of the plurality of DNN setting informationsettable in the first DNN and identifiers indicating each of theplurality of DNN setting information settable in the second DNN may bepreviously designated. In this case, the same identifier may bedesignated for a pair of DNN setting information settable in each of thefirst DNN and the second DNN. The AI data may include an identifier ofDNN setting information set in the first DNN for AI down-scaling of theoriginal image 105. The AI up-scaler 234 that receives the AI data mayperform AI up-scaling on the second image 135 by using the DNN settinginformation indicated by the identifier included in the AI data amongthe plurality of DNN setting information.

Also, according to an embodiment, the AI data may include the DNNsetting information. The AI up-scaler 234 may perform AI up-scaling onthe second image 135 by using the DNN setting information afterobtaining the DNN setting information included in the AI data.

According to an embodiment, when pieces of information (for example, thenumber of convolution layers, the number of filter kernels for eachconvolution layer, a parameter of each filter kernel, and the like)constituting the DNN setting information are stored in a form of alookup table, the AI up-scaler 234 may obtain the DNN settinginformation by combining some values selected from values in the lookuptable, based on information included in the AI data, and perform AIup-scaling on the second image 135 by using the obtained DNN settinginformation.

According to an embodiment, when a structure of DNN corresponding to theup-scaling target is determined, the AI up-scaler 234 may obtain the DNNsetting information, for example, parameters of a filter kernel,corresponding to the determined structure of DNN.

The AI up-scaler 234 obtains the DNN setting information of the secondDNN through the AI data including information related to the first DNN,and performs AI up-scaling on the second image 135 through the secondDNN set based on the obtained DNN setting information, and in this case,memory usage and throughput may be reduced compared to when features ofthe second image 135 are directly analyzed for up-scaling.

According to an embodiment, when the second image 135 includes aplurality of frames, the AI up-scaler 234 may independently obtain DNNsetting information for a certain number of frames, or may obtain commonDNN setting information for entire frames.

FIG. 6 is a diagram showing the second image 135 including a pluralityof frames.

As shown in FIG. 6, the second image 135 may include frames t0 throughtn.

According to an embodiment, the AI up-scaler 234 may obtain DNN settinginformation of a second DNN through AI data, and perform AI up-scalingon the frames t0 through tn based on the obtained DNN settinginformation. In other words, the frames t0 through tn may be processedvia AI up-scaling based on common DNN setting information.

According to another embodiment, the AI up-scaler 234 may perform AIup-scaling on some of the frames t0 through tn, for example, the framest0 through ta, by using ‘A’ DNN setting information obtained from AIdata, and perform AI up-scaling on the frames ta+1 through tb by using‘B’ DNN setting information obtained from the AI data. Also, the AIup-scaler 234 may perform AI up-scaling on the frames tb+1 through tn byusing ‘C’ DNN setting information obtained from the AI data. In otherwords, the AI up-scaler 234 may independently obtain DNN settinginformation for each group including a certain number of frames amongthe plurality of frames, and perform AI up-scaling on frames included ineach group by using the independently obtained DNN setting information.

According to another embodiment, the AI up-scaler 234 may independentlyobtain DNN setting information for each frame forming the second image135. In other words, when the second image 135 includes three frames,the AI up-scaler 234 may perform AI up-scaling on a first frame by usingDNN setting information obtained in relation to the first frame, performAI up-scaling on a second frame by using DNN setting informationobtained in relation to the second frame, and perform AI up-scaling on athird frame by using DNN setting information obtained in relation to thethird frame. DNN setting information may be independently obtained foreach frame included in the second image 135, according to a method ofobtaining DNN setting information based on information (prediction modeinformation, motion information, quantization parameter information, orthe like) provided from the first decoder 232 and information related tothe first image 115 included in the AI data described above. This isbecause the mode information, the quantization parameter information, orthe like may be determined independently for each frame included in thesecond image 135.

According to another embodiment, the AI data may include informationabout to which frame DNN setting information obtained based on the AIdata is valid. For example, when the AI data includes informationindicating that DNN setting information is valid up to the frame ta, theAI up-scaler 234 performs AI up-scaling on the frames t0 through ta byusing DNN setting information obtained based on the AI data. Also, whenanother piece of AI data includes information indicating that DNNsetting information is valid up to the frame tn, the AI up-scaler 234performs AI up-scaling on the frames ta+1 through tn by using DNNsetting information obtained based on the other piece of AI data.

Hereinafter, the AI encoding apparatus 600 for performing AI encoding onthe original image 105 will be described with reference to FIG. 7.

FIG. 7 is a block diagram of a configuration of the AI encodingapparatus 600 according to an embodiment.

Referring to FIG. 7, the AI encoding apparatus 600 may include an AIencoder 610 and a transmitter 630. The AI encoder 610 may include an AIdown-scaler 612 and a first encoder 614. The transmitter 630 may includea data processor 632 and a communicator 634.

In FIG. 7, the AI encoder 610 and the transmitter 630 are illustrated asseparate devices, but the AI encoder 610 and the transmitter 630 may beimplemented through one processor. In this case, the AI encoder 610 andthe transmitter 630 may be implemented through an dedicated processor orthrough a combination of software and general-purpose processor such asAP, CPU or graphics processing unit GPU. The dedicated processor may beimplemented by including a memory for implementing an embodiment of thedisclosure or by including a memory processor for using an externalmemory.

Also, the AI encoder 610 and the transmitter 630 may be configured by aplurality of processors. In this case, the AI encoder 610 and thetransmitter 630 may be implemented through a combination of dedicatedprocessors or through a combination of software and a plurality ofgeneral-purpose processors such as AP, CPU or GPU. The AI down-scaler612 and the first encoder 614 may be implemented through differentprocessors.

The AI encoder 610 performs AI down-scaling on the original image 105and first encoding on the first image 115, and transmits AI data andimage data to the transmitter 630. The transmitter 630 transmits the AIdata and the image data to the AI decoding apparatus 200.

The image data includes data obtained as a result of performing thefirst encoding on the first image 115. The image data may include dataobtained based on pixel values in the first image 115, for example,residual data that is a difference between the first image 115 andprediction data of the first image 115. Also, the image data includesinformation used during a first encoding process of the first image 115.For example, the image data may include prediction mode information,motion information, quantization parameter information used to performthe first encoding on the first image 115, and the like.

The AI data includes information enabling AI up-scaling to be performedon the second image 135 to an up-scaling target corresponding to adown-scaling target of a first DNN. According to an embodiment, the AIdata may include difference information between the original image 105and the first image 115. Also, the AI data may include informationrelated to the first image 115. The information related to the firstimage 115 may include information about at least one of resolution ofthe first image 115, a bitrate of the image data obtained as the resultof performing the first encoding on the first image 115, or a codec typeused during the first encoding of the first image 115.

According to an embodiment, the AI data may include an identifier ofmutually agreed DNN setting information such that the AI up-scaling isperformed on the second image 135 to the up-scaling target correspondingto the down-scaling target of the first DNN.

Also, according to an embodiment, the AI data may include DNN settinginformation settable in a second DNN.

The AI down-scaler 612 may obtain the first image 115 obtained byperforming the AI down-scaling on the original image 105 through thefirst DNN. The AI down-scaler 612 may determine the down-scaling targetof the original image 105, based on a pre-determined standard.

In order to obtain the first image 115 matching the down-scaling target,the AI down-scaler 612 may store a plurality of pieces of DNN settinginformation settable in the first DNN. The AI down-scaler 612 obtainsDNN setting information corresponding to the down-scaling target fromamong the plurality of pieces of DNN setting information, and performsthe AI down-scaling on the original image 105 through the first DNN setin the obtained DNN setting information.

Each of the plurality of pieces of DNN setting information may betrained to obtain the first image 115 of pre-determined resolutionand/or pre-determined quality. For example, any one piece of DNN settinginformation among the plurality of pieces of DNN setting information mayinclude information for obtaining the first image 115 of resolution halfresolution of the original image 105, for example, the first image 115of 2 K (2048×1080) half 4 K (4096×2160) of the original image 105, andanother piece of DNN setting information may include information forobtaining the first image 115 of resolution quarter resolution of theoriginal image 105, for example, the first image 115 of 2 K (2048×1080)quarter 8 K (8192×4320) of the original image 105.

According to an embodiment, when pieces of information (for example, thenumber of convolution layers, the number of filter kernels for eachconvolution layer, a parameter of each filter kernel, and the like)constituting the DNN setting information are stored in a form of alookup table, the AI down-scaler 612 may obtain the DNN settinginformation by combining some values selected from values in the lookuptable, based on the down-scaling target, and perform AI down-scaling onthe original image 105 by using the obtained DNN setting information.

According to an embodiment, the AI down-scaler 612 may determine astructure of DNN corresponding to the down-scaling target, and obtainDNN setting information corresponding to the determined structure ofDNN, for example, obtain parameters of a filter kernel.

The plurality of pieces of DNN setting information for performing the AIdown-scaling on the original image 105 may have an optimized value asthe first DNN and the second DNN are jointly trained. Here, each pieceof DNN setting information includes at least one of the number ofconvolution layers included in the first DNN, the number of filterkernels for each convolution layer, or a parameter of each filterkernel.

The AI down-scaler 612 may set the first DNN with the DNN settinginformation obtained for performing the AI down-scaling on the originalimage 105 to obtain the first image 115 of certain resolution and/orcertain quality through the first DNN. When the DNN setting informationfor performing the AI down-scaling on the original image 105 is obtainedfrom the plurality of pieces of DNN setting information, each layer inthe first DNN may process input data based on information included inthe DNN setting information.

Hereinafter, a method, performed by the AI down-scaler 612, ofdetermining the down-scaling target will be described. The down-scalingtarget may indicate, for example, by how much is resolution decreasedfrom the original image 105 to obtain the first image 115.

According to an embodiment, the AI down-scaler 612 may determine thedown-scaling target based on at least one of a compression ratio (forexample, a resolution difference between the original image 105 and thefirst image 115, target bitrate, or the like), compression quality (forexample, type of bitrate), compression history information, or a type ofthe original image 105.

For example, the AI down-scaler 612 may determine the down-scalingtarget based on the compression ratio, the compression quality, or thelike, which is pre-set or input from a user.

As another example, the AI down-scaler 612 may determine thedown-scaling target by using the compression history information storedin the AI encoding apparatus 600. For example, according to thecompression history information usable by the AI encoding apparatus 600,encoding quality, a compression ratio, or the like preferred by the usermay be determined, and the down-scaling target may be determinedaccording to the encoding quality determined based on the compressionhistory information. For example, the resolution, quality, or the likeof the first image 115 may be determined according to the encodingquality that has been used most often according to the compressionhistory information.

As another example, the AI down-scaler 612 may determine thedown-scaling target based on the encoding quality that has been usedmore frequently than a certain threshold value (for example, averagequality of the encoding quality that has been used more frequently thanthe certain threshold value), according to the compression historyinformation.

As another example, the AI down-scaler 612 may determine thedown-scaling target, based on the resolution, type (for example, a fileformat), or the like of the original image 105.

According to an embodiment, when the original image 105 includes aplurality of frames, the AI down-scaler 612 may independently determinedown-scaling target for a certain number of frames, or may determinedown-scaling target for entire frames.

According to an embodiment, the AI down-scaler 612 may divide the framesincluded in the original image 105 into a certain number of groups, andindependently determine the down-scaling target for each group. The sameor different down-scaling targets may be determined for each group. Thenumber of frames included in the groups may be the same or differentaccording to the each group.

According to another embodiment, the AI down-scaler 612 mayindependently determine a down-scaling target for each frame included inthe original image 105. The same or different down-scaling targets maybe determined for each frame.

Hereinafter, an example of a structure of a first DNN 700 on which AIdown-scaling is based will be described.

FIG. 8 is a diagram showing the first DNN 700 for performing AIdown-scaling on the original image 105.

As shown in FIG. 8, the original image 105 is input to a firstconvolution layer 710. The first convolution layer 710 performs aconvolution process on the original image 105 by using 32 filter kernelshaving a size of 5×5. 32 feature maps generated as a result of theconvolution process are input to a first activation layer 720. The firstactivation layer 720 may assign a non-linear feature to the 32 featuremaps.

The first activation layer 720 determines whether to transmit samplevalues of the feature maps output from the first convolution layer 710to the second convolution layer 730. For example, some of the samplevalues of the feature maps are activated by the first activation layer720 and transmitted to the second convolution layer 730, and some of thesample values are deactivated by the first activation layer 720 and nottransmitted to the second convolution layer 730. Information representedby the feature maps output from the first convolution layer 710 isemphasized by the first activation layer 720.

An output 725 of the first activation layer 720 is input to a secondconvolution layer 730. The second convolution layer 730 performs aconvolution process on input data by using 32 filter kernels having asize of 5×5. 32 feature maps output as a result of the convolutionprocess are input to a second activation layer 740, and the secondactivation layer 740 may assign a non-linear feature to the 32 featuremaps.

An output 745 of the second activation layer 740 is input to a thirdconvolution layer 750. The third convolution layer 750 performs aconvolution process on input data by using one filter kernel having asize of 5×5. As a result of the convolution process, one image may beoutput from the third convolution layer 750. The third convolution layer750 generates one output by using the one filter kernel as a layer foroutputting a final image. According to an embodiment of the disclosure,the third convolution layer 750 may output the first image 115 as aresult of a convolution operation.

There may be a plurality of pieces of DNN setting information indicatingthe numbers of filter kernels of the first, second, and thirdconvolution layers 710, 730, and 750 of the first DNN 700, a parameterof each filter kernel of the first, second, and third convolution layers710, 730, and 750 of the first DNN 700, and the like, and the pluralityof pieces of DNN setting information may be connected to a plurality ofpieces of DNN setting information of a second DNN. The connectionbetween the plurality of pieces of DNN setting information of the firstDNN and the plurality of pieces of DNN setting information of the secondDNN may be realized via joint training of the first DNN and the secondDNN.

In FIG. 8, the first DNN 700 includes three convolution layers (thefirst, second, and third convolution layers 710, 730, and 750) and twoactivation layers (the first and second activation layers 720 and 740),but this is only an example, and the numbers of convolution layers andactivation layers may vary according to an embodiment. Also, accordingto an embodiment, the first DNN 700 may be implemented as an RNN. Inthis case, a CNN structure of the first DNN 700 according to anembodiment of the disclosure is changed to an RNN structure.

According to an embodiment, the AI down-scaler 612 may include at leastone ALU for the convolution operation and the operation of theactivation layer described above. The ALU may be implemented as aprocessor. For the convolution operation, the ALU may include amultiplier that performs multiplication between sample values of theoriginal image 105 or the feature map output from previous layer andsample values of the filter kernel, and an adder that adds result valuesof the multiplication. Also, for the operation of the activation layer,the ALU may include a multiplier that multiplies an input sample valueby a weight used in a pre-determined sigmoid function, a Tan h function,or an ReLU function, and a comparator that compares a multiplicationresult and a certain value to determine whether to transmit the inputsample value to a next layer.

Referring back to FIG. 7, upon receiving the first image 115 from the AIdown-scaler 612, the first encoder 614 may reduce an information amountof the first image 115 by performing first encoding on the first image115. The image data corresponding to the first image 115 may be obtainedas a result of performing the first encoding by the first encoder 614.

The data processor 632 processes at least one of the AI data or theimage data to be transmitted in a certain form. For example, when the AIdata and the image data are to be transmitted in a form of a bitstream,the data processor 632 may process the AI data to be expressed in a formof a bitstream, and transmit the image data and the AI data in a form ofone bitstream through the communicator 634. As another example, the dataprocessor 632 may process the AI data to be expressed in a form ofbitstream, and transmit each of a bitstream corresponding to the AI dataand a bitstream corresponding to the image data through the communicator634. As another example, the data processor 632 may process the AI datato be expressed in a form of a frame or packet, and transmit the imagedata in a form of a bitstream and the AI data in a form of a frame orpacket through the communicator 634.

The communicator 634 transmits AI encoding data obtained as a result ofperforming AI encoding, through a network. The AI encoding data obtainedas the result of performing AI encoding includes the image data and theAI data. The image data and the AI data may be transmitted through asame type of network or different types of networks.

According to an embodiment, the AI encoding data obtained as a result ofprocesses of the data processor 632 may be stored in a data storagemedium including a magnetic medium such as a hard disk, a floppy disk,or a magnetic tape, an optical recording medium such as CD-ROM or DVD,or a magneto-optical medium such as a floptical disk.

Hereinafter, a method of jointly training the first DNN 700 and thesecond DNN 300 will be described with reference to FIG. 9.

FIG. 9 is a diagram for describing a method of training the first DNN700 and the second DNN 300.

In an embodiment, the original image 105 on which AI encoding isperformed through an AI encoding process is reconstructed to the thirdimage 145 via an AI decoding process, and in order to maintainsimilarity between the original image 105 and the third image 145obtained as a result of AI decoding, connectivity is between the AIencoding process and the AI decoding process is required. In otherwords, information lost in the AI encoding process needs to bereconstructed during the AI decoding process, and in this regard, thefirst DNN 700 and the second DNN 300 need to be jointly trained.

For accurate AI decoding, ultimately, quality loss information 830corresponding to a result of comparing a third training image 804 and anoriginal training image 801 shown in FIG. 9 needs to be reduced.Accordingly, the quality loss information 830 is used to train both ofthe first DNN 700 and the second DNN 300.

First, a training process shown in FIG. 9 will be described.

In FIG. 9, the original training image 801 is an image on which AIdown-scaling is to be performed and a first training image 802 is animage obtained by performing AI down-scaling on the original trainingimage 801. Also, the third training image 804 is an image obtained byperforming AI up-scaling on the first training image 802.

The original training image 801 includes a still image or a moving imageincluding a plurality of frames. According to an embodiment, theoriginal training image 801 may include a luminance image extracted fromthe still image or the moving image including the plurality of frames.Also, according to an embodiment, the original training image 801 mayinclude a patch image extracted from the still image or the moving imageincluding the plurality of frames. When the original training image 801includes the plurality of frames, the first training image 802, thesecond training image, and the third training image 804 also eachinclude a plurality of frames. When the plurality of frames of theoriginal training image 801 are sequentially input to the first DNN 700,the plurality of frames of the first training image 802, the secondtraining image and the third training image 804 may be sequentiallyobtained through the first DNN 700 and the second DNN 300.

For joint training of the first DNN 700 and the second DNN 300, theoriginal training image 801 is input to the first DNN 700. The originaltraining image 801 input to the first DNN 700 is output as the firsttraining image 802 via the AI down-scaling, and the first training image802 is input to the second DNN 300. The third training image 804 isoutput as a result of performing the AI up-scaling on the first trainingimage 802.

Referring to FIG. 9, the first training image 802 is input to the secondDNN 300, and according to an embodiment, a second training imageobtained as first encoding and first decoding are performed on the firsttraining image 802 may be input to the second DNN 300. In order to inputthe second training image to the second DNN 300, any one codec amongMPEG-2, H.264, MPEG-4, HEVC, VC-1, VP8, VP9, and AV1 may be used. Inparticular, any one codec among MPEG-2, H.264, MPEG-4, HEVC, VC-1, VP8,VP9, and AV1 may be used to perform first encoding on the first trainingimage 802 and first decoding on image data corresponding to the firsttraining image 802.

Referring to FIG. 9, separate from the first training image 802 beingoutput through the first DNN 700, a reduced training image 803 obtainedby performing legacy down-scaling on the original training image 801 isobtained. Here, the legacy down-scaling may include at least one ofbilinear scaling, bicubic scaling, lanczos scaling, or stair stepscaling.

In order to prevent a structural feature of the first image 115 fromdeviating greatly from a structural feature of the original image 105,the reduced training image 803 is obtained to preserve the structuralfeature of the original training image 801.

Before training is performed, the first DNN 700 and the second DNN 300may be set to pre-determined DNN setting information. When the trainingis performed, structural loss information 810, complexity lossinformation 820, and the quality loss information 830 may be determined.

The structural loss information 810 may be determined based on a resultof comparing the reduced training image 803 and the first training image802. For example, the structural loss information 810 may correspond toa difference between structural information of the reduced trainingimage 803 and structural information of the first training image 802.Structural information may include various features extractable from animage, such as luminance, contrast, histogram, or the like of the image.The structural loss information 810 indicates how much structuralinformation of the original training image 801 is maintained in thefirst training image 802. When the structural loss information 810 issmall, the structural information of the first training image 802 issimilar to the structural information of the original training image801.

The complexity loss information 820 may be determined based on spatialcomplexity of the first training image 802. For example, a totalvariance value of the first training image 802 may be used as thespatial complexity. The complexity loss information 820 is related to abitrate of image data obtained by performing first encoding on the firsttraining image 802. It is defined that the bitrate of the image data islow when the complexity loss information 820 is small.

The quality loss information 830 may be determined based on a result ofcomparing the original training image 801 and the third training image804. The quality loss information 830 may include at least one of anL1-norm value, an L2-norm value, an Structural Similarity (SSIM) value,a Peak Signal-To-Noise Ratio-Human Vision System (PSNR-HVS) value, anMultiscale SSIM (MS-SSIM) value, a Variance Inflation Factor (VIF)value, or a Video Multimethod Assessment Fusion (VMAF) value regardingthe difference between the original training image 801 and the thirdtraining image 804. The quality loss information 830 indicates howsimilar the third training image 804 is to the original training image801. The third training image 804 is more similar to the originaltraining image 801 when the quality loss information 830 is small.

Referring to FIG. 9, the structural loss information 810, the complexityloss information 820 and the quality loss information 830 are used totrain the first DNN 700, and the quality loss information 830 is used totrain the second DNN 300. In other words, the quality loss information830 is used to train both the first and second DNNs 700 and 300.

The first DNN 700 may update a parameter such that final lossinformation determined based on the first through quality lossinformation 810 through 830 is reduced or minimized. Also, the secondDNN 300 may update a parameter such that the quality loss information830 is reduced or minimized.

The final loss information for training the first DNN 700 and the secondDNN 300 may be determined as Equation 1 below.LossDS=a×Structural loss information+b×Complexity lossinformation+c×Quality loss informationLossUS=d×Quality loss information  [Equation 1]

In Equation 1, LossDS indicates final loss information to be reduced orminimized to train the first DNN 700, and LossUS indicates final lossinformation to be reduced or minimized to train the second DNN 300.Also, a, b, c and d may be pre-determined certain weights.

In other words, the first DNN 700 updates parameters in a directionLossDS of Equation 1 is reduced, and the second DNN 300 updatesparameters in a direction LossUS is reduced. When the parameters of thefirst DNN 700 are updated according to LossDS derived during thetraining, the first training image 802 obtained based on the updatedparameters becomes different from a previous first training image 802obtained based on not updated parameters, and accordingly, the thirdtraining image 804 also becomes different from a previous third trainingimage 804. When the third training image 804 becomes different from theprevious third training image 804, the quality loss information 830 isalso newly determined, and the second DNN 300 updates the parametersaccordingly. When the quality loss information 830 is newly determined,LossDS is also newly determined, and the first DNN 700 updates theparameters according to newly determined LossDS. In other words,updating of the parameters of the first DNN 700 leads to updating of theparameters of the second DNN 300, and updating of the parameters of thesecond DNN 300 leads to updating of the parameters of the first DNN 700.In other words, because the first DNN 700 and the second DNN 300 arejointly trained by sharing the quality loss information 830, theparameters of the first DNN 700 and the parameters of the second DNN 300may be jointly optimized.

Referring to Equation 1, it is verified that LossUS is determinedaccording to the quality loss information 830, but this is only anexample and LossUS may be determined based on at least one of thestructural loss information 810 and the complexity loss information 820,and the quality loss information 830.

Hereinabove, it has been described that the AI up-scaler 234 of the AIdecoding apparatus 200 and the AI down-scaler 612 of the AI encodingapparatus 600 store the plurality of pieces of DNN setting information,and methods of training each of the plurality of pieces of DNN settinginformation stored in the AI up-scaler 234 and the AI down-scaler 612will now be described.

As described with reference to Equation 1, the first DNN 700 updates theparameters considering the similarity (the structural loss information810) between the structural information of the first training image 802and the structural information of the original training image 801, thebitrate (the complexity loss information 820) of the image data obtainedas a result of performing first encoding on the first training image802, and the difference (the quality loss information 830) between thethird training image 804 and the original training image 801.

In particular, the parameters of the first DNN 700 may be updated suchthat the first training image 802 having similar structural informationas the original training image 801 is obtained and the image data havinga small bitrate is obtained when first encoding is performed on thefirst training image 802, and at the same time, the second DNN 300performing AI up-scaling on the first training image 802 obtains thethird training image 804 similar to the original training image 801.

A direction in which the parameters of the first DNN 700 are optimizedmay vary by adjusting the weights a, b, and c of Equation 1. Forexample, when the weight b is determined to be high, the parameters ofthe first DNN 700 may be updated by prioritizing a low bitrate over highquality of the third training image 804. Also, when the weight c isdetermined to be high, the parameters of the first DNN 700 may beupdated by prioritizing high quality of the third training image 804over a high bitrate or maintaining of the structural information of theoriginal training image 801.

Also, the direction in which the parameters of the first DNN 700 areoptimized may vary according to a type of codec used to perform firstencoding on the first training image 802. This is because the secondtraining image to be input to the second DNN 300 may vary according tothe type of codec.

In other words, the parameters of the first DNN 700 and the parametersof the second DNN 300 may be jointly updated based on the weights a, b,and c, and the type of codec for performing first encoding on the firsttraining image 802. Accordingly, when the first DNN 700 and the secondDNN 300 are trained after determining the weights a, b, and c each to acertain value and determining the type of codec to a certain type, theparameters of the first DNN 700 and the parameters of the second DNN 300connected and optimized to each other may be determined.

Also, when the first DNN 700 and the second DNN 300 are trained afterchanging the weights a, b, and c, and the type of codec, the parametersof the first DNN 700 and the parameters of the second DNN 300 connectedand optimized to each other may be determined. In other words, theplurality of pieces of DNN setting information jointly trained with eachother may be determined in the first DNN 700 and the second DNN 300 whenthe first DNN 700 and the second DNN 300 are trained while changingvalues of the weights a, b, and c, and the type of codec.

As described above with reference to FIG. 5, the plurality of pieces ofDNN setting information of the first DNN 700 and the second DNN 300 maybe mapped to the information related to the first image. To set such amapping relationship, first encoding may be performed on the firsttraining image 802 output from the first DNN 700 via a certain codecaccording to a certain bitrate and the second training image obtained byperforming first decoding on a bitstream obtained as a result ofperforming the first encoding may be input to the second DNN 300. Inother words, by training the first DNN 700 and the second DNN 300 aftersetting an environment such that the first encoding is performed on thefirst training image 802 of a certain resolution via the certain codecaccording to the certain bitrate, a DNN setting information pair mappedto the resolution of the first training image 802, a type of the codecused to perform the first encoding on the first training image 802, andthe bitrate of the bitstream obtained as a result of performing thefirst encoding on the first training image 802 may be determined. Byvariously changing the resolution of the first training image 802, thetype of codec used to perform the first encoding on the first trainingimage 802 and the bitrate of the bitstream obtained according to thefirst encoding of the first training image 802, the mappingrelationships between the plurality of DNN setting information of thefirst DNN 700 and the second DNN 300 and the pieces of informationrelated to the first image may be determined.

FIG. 10 is a diagram for describing training processes of the first DNN700 and the second DNN by a training apparatus 1000.

The training of the first DNN 700 and the second DNN 300 described withreference FIG. 9 may be performed by the training apparatus 1000. Thetraining apparatus 1000 includes the first DNN 700 and the second DNN300. The training apparatus 1000 may be, for example, the AI encodingapparatus 600 or a separate server. The DNN setting information of thesecond DNN 300 obtained as the training result is stored in the AIdecoding apparatus 200.

Referring to FIG. 10, the training apparatus 1000 initially sets the DNNsetting information of the first DNN 700 and the second DNN 300, inoperations S840 and S845. Accordingly, the first DNN 700 and the secondDNN 300 may operate according to pre-determined DNN setting information.The DNN setting information may include information about at least oneof the number of convolution layers included in the first DNN 700 andthe second DNN 300, the number of filter kernels for each convolutionlayer, the size of a filter kernel for each convolution layer, or aparameter of each filter kernel.

The training apparatus 1000 inputs the original training image 801 intothe first DNN 700, in operation S850. The original training image 801may include a still image or at least one frame included in a movingimage.

The first DNN 700 processes the original training image 801 according tothe initially set DNN setting information and outputs the first trainingimage 802 obtained by performing AI down-scaling on the originaltraining image 801, in operation S855. In FIG. 10, the first trainingimage 802 output from the first DNN 700 is directly input to the secondDNN 300, but the first training image 802 output from the first DNN 700may be input to the second DNN 300 by the training apparatus 1000. Also,the training apparatus 1000 may perform first encoding and firstdecoding on the first training image 802 via a certain codec, and theninput the second training image to the second DNN 300.

The second DNN 300 processes the first training image 802 or the secondtraining image according to the initially set DNN setting informationand outputs the third training image 804 obtained by performing AIup-scaling on the first training image 802 or the second training image,in operation S860.

The training apparatus 1000 calculates the complexity loss information820, based on the first training image 802, in operation S865.

The training apparatus 1000 calculates the structural loss information810 by comparing the reduced training image 803 and the first trainingimage 802, in operation S870.

The training apparatus 1000 calculates the quality loss information 830by comparing the original training image 801 and the third trainingimage 804, in operation S875.

The initially set DNN setting information is updated in operation S880via a back propagation process based on the final loss information. Thetraining apparatus 1000 may calculate the final loss information fortraining the first DNN 700, based on the complexity loss information820, the structural loss information 810, and the quality lossinformation 830.

The second DNN 300 updates the initially set DNN setting information inoperation S885 via a back propagation process based on the quality lossinformation 830 or the final loss information. The training apparatus1000 may calculate the final loss information for training the secondDNN 300, based on the quality loss information 830.

Then, the training apparatus 1000, the first DNN 700, and the second DNN300 may repeat operations S850 through S885 until the final lossinformation is minimized to update the DNN setting information. At thistime, during each repetition, the first DNN 700 and the second DNN 300operate according to the DNN setting information updated in the previousoperation.

Table 1 below shows effects when AI encoding and AI decoding areperformed on the original image 105 according to an embodiment of thedisclosure and when encoding and decoding are performed on the originalimage 105 via HEVC.

TABLE 1 Information Subjective Image Amount (Bitrate) Quality Score(Mbps) (VMAF) Frame Al Encoding/ Al Encoding/ Content Resolution NumberHEVC Al Decoding HEVC Al Decoding Content_01 8K 300 frames 46.3 21.494.80 93.54 Content_02 (7680 × 4320) 46.3 21.6 98.05 98.98 Content_0346.3 22.7 96.08 96.00 Content_04 46.1 22.1 86.26 92.00 Content_05 45.422.7 93.42 92.98 Content_06 46.3 23.0 95.99 95.61 Average 46.11 22.2594.10 94.85

As shown in Table 1, despite subjective image quality when AI encodingand AI decoding are performed on content including 300 frames of 8 Kresolution, according to an embodiment of the disclosure, is higher thansubjective image quality when encoding and decoding are performed viaHEVC, a bitrate is reduced by at least 50%.

FIG. 11 is a diagram of an apparatus 20 for performing AI down-scalingon the original image 105 and an apparatus 40 for performing AIup-scaling on the second image 135.

The apparatus 20 receives the original image 105 and provides image data25 and AI data 30 to the apparatus 40 by using an AI down-scaler 1124and a transformation-based encoder 1126. According to an embodiment, theimage data 25 corresponds to the image data of FIG. 1 and the AI data 30corresponds to the AI data of FIG. 1. Also, according to an embodiment,the transformation-based encoder 1126 corresponds to the first encoder614 of FIG. 7 and the AI down-scaler 1124 corresponds to the AIdown-scaler 612 of FIG. 7.

The apparatus 40 receives the AI data 30 and the image data 25 andobtains the third image 145 by using a transformation-based decoder 1146and an AI up-scaler 1144. According to an embodiment, thetransformation-based decoder 1146 corresponds to the first decoder 232of FIG. 2 and the AI up-scaler 1144 corresponds to the AI up-scaler 234of FIG. 2.

According to an embodiment, the apparatus 20 includes a CPU, a memory,and a computer program including instructions. The computer program isstored in the memory. According to an embodiment, the apparatus 20performs functions to be described with reference to FIG. 11 accordingto execution of the computer program by the CPU. According to anembodiment, the functions to be described with reference to FIG. 11 areperformed by a dedicated hardware chip and/or the CPU.

According to an embodiment, the apparatus 40 includes a CPU, a memory,and a computer program including instructions. The computer program isstored in the memory. According to an embodiment, the apparatus 40performs functions to be described with reference to FIG. 11 accordingto execution of the computer program by the CPU. According to anembodiment, the functions to be described with reference to FIG. 11 areperformed by a dedicated hardware chip and/or the CPU.

In FIG. 11, a configuration controller 1122 receives at least one inputvalue 10. According to an embodiment, the at least one input value 10may include at least one of a target resolution difference for the AIdown-scaler 1124 and the AI up-scaler 1144, a bitrate of the image data25, a bitrate type of the image data 25 (for example, a variable bitratetype, a constant bitrate type, or an average bitrate type), or a codectype for the transformation-based encoder 1126. The at least one inputvalue 10 may include a value pre-stored in the apparatus 20 or a valueinput from a user.

The configuration controller 1122 controls operations of the AIdown-scaler 1124 and the transformation-based encoder 1126, based on thereceived input value 10. According to an embodiment, the configurationcontroller 1122 obtains DNN setting information for the AI down-scaler1124 according to the received input value 10, and sets the AIdown-scaler 1124 with the obtained DNN setting information. According toan embodiment, the configuration controller 1122 may transmit thereceived input value 10 to the AI down-scaler 1124 and the AIdown-scaler 1124 may obtain the DNN setting information for performingAI down-scaling on the original image 105, based on the received inputvalue 10. According to an embodiment, the configuration controller 1122may provide, to the AI down-scaler 1124, additional information, forexample, color format (luminance component, chrominance component, redcomponent, green component, or blue component) information to which AIdown-scaling is applied and tone mapping information of a high dynamicrange (HDR), together with the input value 10, and the AI down-scaler1124 may obtain the DNN setting information considering the input value10 and the additional information. According to an embodiment, theconfiguration controller 1122 transmits at least a part of the receivedinput value 10 to the transformation-based encoder 1126 and thetransformation-based encoder 1126 performs first encoding on the firstimage 115 via a bitrate of a certain value, a bitrate of a certain type,and a certain codec.

The AI down-scaler 1124 receives the original image 105 and performs anoperation described with reference to at least one of FIG. 1, 7, 8, 9,or 10 to obtain the first image 115.

According to an embodiment, the AI data 30 is provided to the apparatus40. The AI data 30 may include at least one of resolution differenceinformation between the original image 105 and the first image 115, orinformation related to the first image 115. The resolution differenceinformation may be determined based on the target resolution differenceof the input value 10, and the information related to the first image115 may be determined based on at least one of a target bitrate, thebitrate type, or the codec type. According to an embodiment, the AI data30 may include parameters used during the AI up-scaling. The AI data 30may be provided from the AI down-scaler 1124 to the apparatus 40.

The image data 25 is obtained as the original image 105 is processed bythe transformation-based encoder 1126, and is transmitted to theapparatus 40. The transformation-based encoder 1126 may process thefirst image 115 according to MPEG-2, H.264 AVC, MPEG-4, HEVC, VC-1, VP8,VP9, or VA1.

A configuration controller 1142 controls an operation of the AIup-scaler 1144, based on the AI data 30. According to an embodiment, theconfiguration controller 1142 obtains the DNN setting information forthe AI up-scaler 1144 according to the received AI data 30, and sets theAI up-scaler 1144 with the obtained DNN setting information. Accordingto an embodiment, the configuration controller 1142 may transmit thereceived AI data 30 to the AI up-scaler 1144 and the AI up-scaler 1144may obtain the DNN setting information for performing AI up-scaling onthe second image 135, based on the AI data 30. According to anembodiment, the configuration controller 1142 may provide, to the AIup-scaler 1144, additional information, for example, the color format(luminance component, chrominance component, red component, greencomponent, or blue component) information to which AI up-scaling isapplied, and the tone mapping information of HDR, together with the AIdata 30, and the AI up-scaler 1144 may obtain the DNN settinginformation considering the AI data 30 and the additional information.According to an embodiment, the AI up-scaler 1144 may receive the AIdata 30 from the configuration controller 1142, receive at least one ofprediction mode information, motion information, or quantizationparameter information from the transformation-based decoder 1146, andobtain the DNN setting information based on the AI data 30 and at leastone of the prediction mode information, the motion information, and thequantization parameter information.

The transformation-based decoder 1146 may process the image data 25 toreconstruct the second image 135. The transformation-based decoder 1146may process the image data 25 according to MPEG-2, H.264 AVC, MPEG-4,HEVC, VC-1, VP8, VP9, or AV1.

The AI up-scaler 1144 may obtain the third image 145 by performing AIup-scaling on the second image 135 provided from thetransformation-based decoder 1146, based on the set DNN settinginformation.

The AI down-scaler 1124 may include a first DNN and the AI up-scaler1144 may include a second DNN, and according to an embodiment, DNNsetting information for the first DNN and second DNN are trainedaccording to the training method described with reference to FIGS. 9 and10.

In FIGS. 12 through 25, a relationship between AI data and image data inAI encoding data will be described, together with a data structure ofthe AI data. Hereinafter, an up-scaling DNN is a DNN used to AI up-scalea low resolution image such as the second image 135 to a high resolutionimage such as the third image 145, like the second DNN 300 of FIG. 3.Up-scaling DNN information indicates DNN configuration informationspecified according to the AI data and the up-scaling DNN may beconfigured based on the up-scaling DNN information. The low resolutionimage indicates an image of low resolution, such as the first image 115and the second image 135. The high resolution image indicates an imageof high resolution, such as the original image 105 and the third image145.

In FIG. 12, a corresponding relationship between image data 1200 and AIdata 1240 is described together with structures of the image data 1200and AI data 1240.

In FIG. 12, a video-frame group-frame layer structure of the image data1200 is described. A video 1202 of FIG. 12 is a data unit including allconsecutive frames of the image data 1200. Parameter information of avideo parameter set may be applied to all frames included in the video1202. The video parameter set is included in a video header 1204.

The video 1202 may include a plurality of frame groups. The frame groupis a data unit including one or more consecutive frames sharingparameter information of a frame group parameter set. The frame groupmay be a group of pictures (GOP) or a coded video sequence (CVS). Theframe group parameter set may be included in a frame group header. Forexample, a frame group parameter set of a first frame group 1210 may beincluded in a first frame group header 1212. Also, a frame groupparameter set of a second frame group 1214 may be included in a secondframe group header 1216.

One frame group is independently encoded without referring to anotherframe group. The frame group may include an instantaneous decodingrefresh (IDR) frame or intra random access picture (IRAP) frame encodedwithout referring to another frame. Also, remaining frames of the framegroup are encoded by referring to the IDR frame (or IRAP frame).Accordingly, the first frame group 1210 may be independently encodedwithout referring to another frame group of the video 1202. Also, afirst frame 1220 that is a frame of the first frame group 1210 encodedfirst is an IDR frame (or IRAP frame). Remaining frames of the firstframe group 1210 including a second frame 1230 are encoded by referringto the first frame 1220.

A frame indicates one still image included in a video. A frame headermay include a frame parameter set including parameter informationapplied to a frame. For example, a first frame header 1222 of the firstframe 1220 may include a frame parameter set applied to the first frame1220. Similarly, a second frame header 1232 of the second frame 1230 mayinclude a frame parameter set applied to the second frame 1230.

A classification method of the AI data 1240 according to the video-framegroup-frame layer structure described in FIG. 12 will be described. TheAI data 1240 may be classified into video AI data 1242, frame group AIdata 1250, and frame AI data 1260 according to an application range. Thevideo AI data 1242 denote AI data commonly applied to all frame groupsincluded in the video 1202. Also, the frame group AI data 1250 denote AIdata commonly applied to frames included in a current frame group. Also,the frame AI data 1260 denote AI data applied to a current frame.

The video AI data 1242 corresponds to the video header 1204.Accordingly, the video AI data 1242 may be decoded in parallel with thevideo header 1204. Alternatively, the video AI data 1242 may be decodedimmediately before decoding of the video header 1204. Alternatively, thevideo AI data 1242 may be decoded immediately after decoding of thevideo header 1204.

The frame group AI data 1250 corresponds to a frame group header.According to FIG. 12, first frame group AI data 1252 corresponds to thefirst frame group header 1212. Also, second frame group AI data 1254corresponds to a second frame group header 1216. The first frame groupAI data 1252 and the second frame group AI data 1254 may be decoded inparallel with the first frame group header 1212 and the second framegroup header 1216, respectively. Alternatively, the first frame group AIdata 1252 and the second frame group AI data 1254 may be decodedimmediately before decoding of the first frame group header 1212 and thesecond frame group header 1216, respectively. Alternatively, the firstframe group AI data 1252 and the second frame group AI data 1254 may bedecoded immediately after decoding of the first frame group header 1212and the second frame group header 1216, respectively.

The frame AI data 1260 corresponds to a frame header. According to FIG.12, first frame AI data 1262 corresponds to the first frame header 1222.Also, second frame AI data 1264 corresponds to the second frame header1232. The first frame AI data 1262 and the second frame AI data 1264 maybe decoded in parallel with the first frame header 1222 and the secondframe header 1232, respectively. Alternatively, the first frame AI data1262 and the second frame AI data 1264 may be decoded immediately beforedecoding of the first frame header 1222 and the second frame header1232, respectively. Alternatively, the first frame AI data 1262 and thesecond frame AI data 1264 may be decoded immediately after decoding ofthe first frame header 1222 and the second frame header 1232,respectively.

According to an embodiment of the disclosure, the data processor 632 ofFIG. 7 may generate AI encoding data in a single file format includingboth the image data 1200 and the AI data 1240. The communicator 634transmits the AI encoding data in the single file format to acommunicator 212 of FIG. 2. In the specification, a file denotes a groupof data stored in a memory. Also, a video file denotes a group of imagedata stored in a memory and the image data may be implemented in a formof a bitstream.

According to an embodiment of the disclosure, the AI data 1240 may notbe embedded in the image data 1200 and may be configured separately fromthe image data 1200 in a single file. Accordingly, despite the AIencoding data is configured in a single file, because the AI data 1240and the image data 1200 are separated, the AI data 1240 and/or the imagedata 1200 may include information about synchronization of the AI data1240 and the image data 1200.

The communicator 212 may receive AI encoding data. Also, the parser 214may extract AI data and image data from the AI encoding data. Also, theoutputter 216 transmits the image data to the first decoder 232 and theAI data to the AI up-scaler 234. Also, the first decoder 232 generates alow resolution image by decoding the image data. Also, the AI up-scaler234 obtains up-scaling DNN information suitable for up-scaling of thelow resolution image, based on the AI data, and AI up-scales the lowresolution image by using an up-scaling DNN set according to theup-scaling DNN information.

According to an embodiment of the disclosure, synchronization data forsynchronization of the AI data and the image data may be included in theAI encoding data. The synchronization data may be included in the AIencoding data independently from the AI data and the image data.Alternatively, the synchronization data may be included in the AI dataor the image data. The parser 214 may synchronize the image data and theAI data according to the synchronization data. Alternatively, the AIup-scaler 234 may synchronize the image data and the AI data accordingto the synchronization data. The up-scaling DNN information suitable forAI up-scaling the low resolution image may be selected according to thesynchronization data.

According to an embodiment of the disclosure, the AI data 1240 may beembedded in the image data 1200. For example, the video AI data 1242 maybe embedded in the video header 1204. Accordingly, the video header 1204may include the video AI data 1242 together with the video parameterset. Thus, the video AI data 1242 may be decoded together with the videoparameter set. Alternatively, the video AI data 1242 may be embedded ina single file to be located before or after the video header 1204,independently from the video header 1204. Accordingly, the video AI data1242 may be decoded immediately before or after decoding of the videoheader 1204.

Similarly, the first frame group header 1212 may be included in thefirst frame group AI data 1252 together with the frame group parameterset. Thus, the first frame group AI data 1252 may be decoded togetherwith the frame group parameter set. Alternatively, the first frame groupAI data 1252 may be embedded in a single file to be located before orafter the first frame group header 1212, independently from the firstframe group header 1212. Accordingly, the first frame group AI data 1252may be decoded immediately before or after decoding of the first framegroup header 1212.

Similarly, the first frame header 1222 may include the first frame AIdata 1262 together with the frame parameter set. Thus, the first frameAI data 1262 may be decoded together with the frame parameter set.Alternatively, the first frame AI data 1262 may be embedded in a singlefile to be located before or after the first frame header 1222,independently from the first frame header 1222. Accordingly, the firstframe AI data 1262 may be decoded immediately before or after decodingof the first frame header 1222.

A flow of data in the AI decoding apparatus 200 when AI data is embeddedin image data will be described with reference to FIG. 13A.

In AI encoding data, when the AI data is embedded in the image data, theAI data is unable to be decoded independently without decoding of theimage data. Thus, the AI data embedded in the image data is extractedfrom the image data while the first decoder 232 decodes the image data.Also, the AI data extracted from the image data is transmitted from thefirst decoder 232 to the AI up-scaler 234.

According to an embodiment of the disclosure, a part of the AI data maybe embedded in the image data and the remaining part of the AI data maybe included in the AI encoding data independently from the image data.For example, video AI data may be included in the AI encoding dataindependently from the image data and frame group AI data and frame AIdata may be embedded in the image data.

First AI data present independently from the image data may be separatedfrom the image data by the parser 214. Also, the first AI data separatedfrom the image data may be transmitted from the outputter 216 to the AIup-scaler 234. The first AI data may be video AI data and/or videosegment AI data.

Also, second AI data embedded in the image data is extracted from theimage data by the first decoder 232. The extracted second AI data istransmitted from the first decoder 232 to the AI up-scaler 234. Also,the AI up-scaler 234 obtains up-scaling DNN information required for AIup-scaling of a low resolution image, according to the first AI data andthe second AI data. The second AI data may be frame group AI data and/orframe AI data.

According to an embodiment of the disclosure, the data processor 632 mayseparately generate a file corresponding to the image data 1200 and afile corresponding to the AI data 1240. Accordingly, the communicator634 transmits the AI encoding data to the communicator 212 in two fileformats. Thus, the communicator 634 may transmit the file correspondingto the image data 1200 and the file corresponding to the AI data 1240via different communication channels. Also, the communicator 634 maysequentially transmit the file corresponding to the image data 1200 andthe file corresponding to the AI data 1240 with a time difference.

According to an embodiment of the disclosure, according to thecorresponding relationship between the image data 1200 and the AI data1240 described with reference to FIG. 12, the file corresponding to theAI data 1240 may be decoded dependently on a decoding process of thefile corresponding to the image data 1200. Also, because the filecorresponding to the image data 1200 and the file corresponding to theAI data 1240 are separated, the file corresponding to the image data1200 and the file corresponding to the AI data 1240 may includeinformation about synchronization of the two files.

FIG. 13B is a diagram for describing a flow of data in the AI decodingapparatus 200, when AI data and image data are separated and configuredin two files.

The communicator 212 may separately receive a file including image dataand a file including AI data, instead of a single file including AIencoding data. Also, the communicator 212 may obtain synchronizationdata required for synchronization of the image data and the AI data fromthe file including the image data or the file including the AI data.According to an embodiment of the disclosure, the synchronization datamay be transmitted from a separate file. In FIG. 13B, thesynchronization data is represented as data independent from the AIdata, but according to an embodiment of the disclosure, the AI data orthe image data may include the synchronization data.

According to an embodiment of the disclosure, the parser 214 maysynchronize the image data and the AI data according to thesynchronization data. Also, the outputter 216 may transmit thesynchronized image data to the first decoder 232 and the synchronized AIdata to the AI up-scaler 234.

According to an embodiment of the disclosure, the outputter 216 maytransmit the image data to the first decoder 232. Also, the AI data andthe synchronization data may be transmitted to the AI up-scaler 234. TheAI up-scaler 234 AI up-scales a low resolution image output from thefirst decoder 232 by using up-scaling DNN information obtained accordingto the synchronization data and the AI data.

FIG. 14 illustrates an example of AI encoding data when AI data 1420 andimage data 1431 are separated in a single file. In FIG. 14, the AIencoding data is included in a video file 1400 of a certain containerformat. The certain container format may be MP4, AVI, MKV, or FLV.

The video file 1400 includes a metadata box 1410 and a media data box1430. Information about media data included in the media data box 1430is included in the metadata box 1410. For example, the metadata box 1410may include information about a type of media data, a type of codec usedto encode the media data, and a reproduction time of media.

The metadata box 1410 may include synchronization data 1415 and the AIdata 1420. The synchronization data 1415 and the AI data 1420 are storedin the metadata box 1410 after being encoded according to an encodingmethod provided by the certain container format.

The parser 214 may extract the synchronization data 1415 and the AI data1420 from the metadata box 1410. Also, the parser 214 may extract theimage data 1431 from the media data box 1430. The outputter 216 maytransmit the image data 1431 to the first decoder 232 and transmit theAI data 1420 to the AI up-scaler 234, according to the synchronizationdata 1415. Alternatively, the outputter 216 may transmit thesynchronization data 1415 to the AI up-scaler 234 and the AI up-scaler234 may synchronize the image data 1431 and the AI data 1420, accordingto the synchronization data 1415.

The AI data 1420 may include video AI data 1422, frame group AI data1424, and frame AI data 1426. The video AI data 1422 may be set tocorrespond to a video header 1432, the frame group AI data 1424 may beset to correspond to a frame group header 1436, and the frame AI data1426 may be set to correspond to a frame header 1440.

According to an embodiment of the disclosure, when the same up-scalingDNN information is used for all frames of a video, the frame group AIdata 1424 and the frame AI data 1426 may be omitted from the AI data1420. Alternatively, when up-scaling DNN information is adaptivelyobtained for each frame group unit and the same up-scaling DNNinformation is used for all frames of a frame group, the frame AI data1426 may be omitted from the AI data 1420.

The synchronization data 1415 includes information about synchronizationof the video AI data 1422, the frame group AI data 1424, and the frameAI data 1426, and the video header 1432, the frame group header 1436,and the frame header 1440. For example, the synchronization data 1415may include reproduction order information or decoding order informationof the image data 1431 of the media data box 1430. Accordingly, the AIup-scaler 234 may obtain up-scaling DNN information required for AIup-scaling of a low resolution image, from AI data determined accordingto the reproduction order information or decoding order information ofthe synchronization data 1415.

For example, in order to AI up-scale a low resolution image of a frame1438, the parser 214 or the AI up-scaler 234 may determine the framegroup AI data 1424 corresponding to a frame group 1434 or the frame AIdata 1426 corresponding to the frame 1438, based on the synchronizationdata 1415. Also, the AI up-scaler 234 may obtain up-scaling DNNinformation for AI up-scaling of the low resolution image of the frame1438, considering the video AI data 1422 applied to all frames togetherwith the frame group AI data 1424 and the frame AI data 1426.

The AI data 1420 of the metadata box 1410 may be decoded before theimage data 1431 of the media data box 1430. Accordingly, the AIup-scaler 234 may obtain the up-scaling DNN information before decodingof the image data 1431, according to the AI data 1420. The up-scalingDNN information may be applied to the entire video. Alternatively,different pieces of up-scaling DNN information may be obtained for eachframe group for adaptive AI up-scaling of a frame group unit.Alternatively, the up-scaling DNN information may be pre-obtaineddifferently for each frame for adaptive AI up-scaling of a frame unit.

The AI up-scaler 234 may decode the AI data 1420 of the metadata box1410, according to a decoding order of the image data 1431 of the mediadata box 1430. The video AI data 1422 may be decoded immediately beforeor after decoding of the video header 1432. Alternatively, the video AIdata 1422 may be decoded in parallel with the video header 1432. Todecode the video AI data 1422 according to a decoding order of the videoheader 1432, the synchronization data 1415 may be referred to.

Similarly, the AI up-scaler 234 may decode the frame group AI data 1424immediately before or after decoding of the frame group header 1436 bythe first decoder 232. Alternatively, the AI up-scaler 234 may decodethe frame group AI data 1424 in parallel with decoding of the framegroup header 1436 by the first decoder 232. To decode the frame group AIdata 1424 according to a decoding order of the frame group header 1436,the synchronization data 1415 may be referred to.

Also, the AI up-scaler 234 may decode the frame AI data 1426 immediatelybefore or after decoding of the frame header 1440 by the first decoder232. Alternatively, the AI up-scaler 234 may decode the frame AI data1426 in parallel with decoding of the frame header 1440 by the firstdecoder 232. To decode the frame AI data 1426 according to a decodingorder of the frame header 1440, the synchronization data 1415 may bereferred to.

In FIG. 14, for convenience of description, one metadata box 1410 andone media data box 1430 are included in the video file 1400. However,the video file 1400 may include two or more metadata boxes and two ormore media data boxes. Accordingly, two or more image data segments inwhich image data is split in certain time units may be stored in the twoor more media data boxes. Also, information about the image datasegments stored in the two or more media data boxes may be included inthe two or more metadata boxes. Also, the two or more metadata boxes mayeach include AI data.

FIG. 15A illustrates an example of AI encoding data when AI data isembedded in image data 1505.

A video file 1500 includes a metadata box 1502 and a media data box 1504like the video file 1400 of FIG. 14. Because the AI data is embedded inthe image data 1505, the metadata box 1502 does not include the AI data.Instead, the image data 1505 in which the AI data is embedded isincluded in the media data box 1504. The AI data may be encodedaccording to a video codec of the image data 1505. For example, thevideo codec of the image data 1505 may be H.264, HEVC, AVS2.0, and Xvid.

Accordingly, the parser 214 does not extract the AI data from themetadata box 1502. Instead, the first decoder 232 may extract the AIdata from the image data 1505 and transmit the extracted AI data to theAI up-scaler 234. Also, the AI up-scaler 234 may AI up-scale a lowresolution image reconstructed by the first decoder 232, based onup-scaling DNN information obtained via the AI data.

Unlike the video file 1400 of FIG. 14, because the AI data is embeddedin the image data 1505 according to a decoding order of the image data1505, the video file 1500 may not include synchronization data.Accordingly, the AI data is sequentially decoded as the image data 1505is decoded.

Video AI data 1508 may be located immediately after a video header 1506including parameter information of a video. Accordingly, the video AIdata 1508 may be decoded after video parameters included in the videoheader 1506 are decoded. According to an embodiment of the disclosure,unlike FIG. 15A, the video AI data 1508 may be located immediatelybefore the video header 1506.

Frame group AI data 1514 may be located immediately after a frame groupheader 1512 including parameter information of a frame group 1510.Accordingly, the frame group AI data 1514 may be decoded after framegroup parameters included in the frame group header 1512 are decoded.According to an embodiment of the disclosure, unlike FIG. 15A, the framegroup AI data 1514 may be located immediately before the frame groupheader 1512. Decoding orders of pieces of frame group AI data and framegroup headers of remaining frame groups decoded after the frame group1510 may be determined in the same manner as decoding orders of theframe group AI data 1514 and the frame group header 1512.

Frame AI data 1520 may be located immediately after a frame header 1518including parameter information of a frame 1516. Accordingly, the frameAI data 1520 may be decoded after frame group parameters included in theframe header 1518 are decoded. According to an embodiment of thedisclosure, unlike FIG. 15A, the frame AI data 1520 may be locatedimmediately before the frame header 1518. Decoding orders of pieces offrame AI data and frame headers of remaining frames decoded after theframe 1516 may be determined in the same manner as decoding orders ofthe frame AI data 1520 and the frame header 1518.

FIG. 15A illustrates another example of AI encoding data when AI data isembedded in image data 1525.

Like the video file 1500 of FIG. 15A, a video file 1521 includes ametadata box 1522 and a media data box 1524. Also, the metadata box 1522does not include the AI data, and instead, the image data 1525 in whichthe AI data is embedded is included in the media data box 1524. However,unlike the video file 1500 of FIG. 15A, a data header corresponding tothe AI data is embedded in the video file 1521.

Video AI data 1528 may be included in a video header 1526 includingparameter information of a video. Accordingly, the video AI data 1528may be decoded together with video parameters included in the videoheader 1526.

Frame group AI data 1534 may be included in a frame group header 1532including parameter information of a frame group 1530. Accordingly, theframe group AI data 1534 may be decoded together with frame groupparameters included in the frame group header 1532. Frame group AI dataof remaining frame groups decoded after the frame group 1530 may also beincluded in the frame group header 1532.

Frame AI data 1540 may be included in a frame header 1538 includingparameter information of a frame 1536. Accordingly, the frame AI data1540 may be decoded together with frame group parameters included in theframe header 1538. Frame AI data of remaining frames decoded after theframe 1536 may also be included in the frame header 1538.

FIG. 15C illustrates an example of AI encoding data when partial AI datais embedded in image data 1557 and remaining AI data is separated fromthe image data 1557.

Like the video file 1500 of FIG. 15A, a video file 1550 includes ametadata box 1552 and a media data box 1556. The metadata box 1552includes video AI data 1554 applied to all frames of a video. Also,frame group AI data 1564 and frame AI data 1570 are included in theimage data 1557 of the media data box 1556.

Unlike the video AI data 1508 of FIG. 15A and the video AI data 1528 ofFIG. 15B, the video AI data 1554 included in the metadata box 1552 maybe decoded before decoding of the image data 1557. Also, the frame groupAI data 1564 and the frame AI data 1570 may be sequentially decoded asthe image data 1557 is decoded.

Thus, the parser 214 may extract the video AI data 1554 from themetadata box 1552. Also, the communicator 212 may transmit the video AIdata 1554 to the AI up-scaler 234. Also, the communicator 212 maytransmit the image data 1557 to the first decoder 232. Also, the firstdecoder 232 may decode the image data 1557 to reconstruct a lowresolution image and may extract the frame group AI data 1564 and theframe AI data 1570. Also, the first decoder 232 may transmit the framegroup AI data 1564 and the frame AI data 1570 to the AI up-scaler 234.Also, the AI up-scaler 234 may obtain up-scaling DNN information for AIup-scaling of the low resolution image, according to the video AI data1554, the frame group AI data 1564, and the frame AI data 1570.

The frame group AI data 1564 may be located immediately after a framegroup header 1562 including parameter information of a frame group 1560.However, according to an embodiment of the disclosure, the frame groupAI data 1564 may be located immediately before the frame group header1562. Also, the frame group AI data 1564 may be included in the framegroup header 1562.

The frame AI data 1570 may be located immediately after a frame header1568 including parameter information of a frame 1566. However, accordingto an embodiment of the disclosure, the frame AI data 1570 may belocated immediately before the frame header 1568. Also, the frame AIdata 1570 may be included in the frame header 1568.

In FIG. 15C, only the video AI data 1554 is included in the metadata box1552, but the frame group AI data 1564 may be additionally included inthe metadata box 1552. Alternatively, a part of the frame group AI data1564 may be included in the metadata box 1552. Alternatively, a part ofthe frame AI data 1570 may be included in the metadata box 1552.

In FIGS. 15A and 15C, the frame group AI data 1514 and 1564 and theframe AI data 1520 and 1570 embedded in the media data boxes 1504 and1556 may be embedded in a form of a supplementary enhancementinformation (SEI) message. An SEI message is a data unit includingadditional information about an image, which is not necessarily requiredwhen decoding the image. The SEI message may be transmitted in a framegroup unit or frame unit. Also, the SEI message may be extracted by thefirst decoder 232 and transmitted to the AI up-scaler 234 like thesecond AI data described with reference to FIG. 13A.

FIG. 16 illustrates an example of AI encoding data split in videosegment units when AI data and image data are separated as in FIG. 14.

When the size of metadata including AI data is large or the image datais live-streamed through a communication channel, the AI encoding datamay be split in video segment units and stored in a video file 1600 toreduce overhead required to process the metadata including the AI data.A video segment is a part of a video and includes a frame of a certaintime. For example, the video segment may include only one or more framegroups. When the video segment includes one frame group, the video file1600 may include the number of video segments equal to that of framegroups of the image data.

The video segments may each include a metadata box and a media data box.The metadata including the AI data is split and stored in the pluralityof video segments. Accordingly, the AI data is split and stored not onlyin a metadata box 1610 regarding the entire image data, but also inmetadata boxes regarding the video segments. Thus, when a certain partof the image data is AI up-scaled from a low resolution image, the AIdata for obtaining up-scaling DNN information suitable to the certainpart may be more quickly obtained when the AI data is split and storedin the metadata boxes regarding the video segments as well as themetadata box 1610 compared to when all pieces of AI data are stored inthe metadata box 1610 regarding the entire image data.

For example, when reproduction is performed from a current videosegment, for AI up-scaling of a low resolution image of the currentvideo segment, only video AI data 1612 of the metadata box 1610 and theAI data of a segment metadata box 1630 of a current video segment databox 1620 may be referred to. Also, AI data of metadata boxes of othervideo segments are not referred to. Thus, overhead according to decodingof the AI data is reduced.

Also, when the image data is live-streamed, the AI data is nottransmitted at once during initial reproduction but may be split andtransmitted in video segment units. Thus, because the AI data is splitand transmitted sequentially, overhead according to decoding of the AIdata may be reduced. Accordingly, splitting and transmitting in videosegment units may be advantageous.

In FIG. 16, the metadata box 1610 regarding the entire image dataincludes the video AI data 1612. The video AI data 1612 is applied toall video segments included in the video. The metadata box 1610 may bedecoded before the current video segment data box 1620.

The current video segment data box 1620 includes the segment metadatabox 1630 and a segment media data box 1640. The segment metadata box1630 may include synchronization data 1631 and AI data 1632. Also, thesegment media data box 1640 includes video segment data 1641.

The AI data 1632 of the current video segment data box 1620 may includevideo segment AI data 1634, frame group AI data 1636, and frame AI data1638. The video segment AI data 1634 is applied to all frame groupsincluded in a current video segment. Also, the frame group AI data 1636is applied to all frames included in a current frame group. The frame AIdata 1638 is applied to a current frame.

According to an embodiment of the disclosure, when the same up-scalingDNN information is used for all frames of a video segment, the framegroup AI data 1636 and the frame AI data 1638 may be omitted from the AIdata 1632 of the current video segment data box 1620. Alternatively,when up-scaling DNN information is adaptively determined for each framegroup unit and the same up-scaling DNN information is used for allframes of the frame group, the frame AI data 1638 may be omitted fromthe AI data 1632 of the current video segment data box 1620.

According to an embodiment of the disclosure, when a video segmentincludes one frame group, the video segment AI data 1634 may be omittedfrom the AI data 1632 of the current video segment data box 1620. Here,the frame group AI data 1636 may perform functions as the video segmentAI data 1634. Alternatively, when a video segment includes only oneframe group and the same up-scaling DNN information is used for allframes of the frame group, the video segment AI data 1634 and the frameAI data 1638 may be omitted from the AI data 1632 of the current videosegment data box 1620. Then, AI up-scaling may be applied to all framesof the video segment, based on the up-scaling DNN information accordingto the frame group AI data 1636. The synchronization data 1631 includesinformation about synchronization of the video segment AI data 1634, theframe group AI data 1636, and the frame AI data 1638, and a videosegment header 1642, a frame group header 1646, and a frame header 1648.The video segment header 1642 includes a video segment parametercommonly applied to frames included in the video segment. For example,the synchronization data 1631 may include reproduction order informationor decoding order information of the video segment data 1641 of thesegment media data box 1640. Accordingly, the AI up-scaler 234 mayobtain up-scaling information required for AI up-scaling of the lowresolution image from AI data determined according to thesynchronization data 1631.

For example, in order to up-scale a low resolution image of a frame1649, the parser 214 or the AI up-scaler 234 may obtain the frame groupAI data 1636 corresponding to the frame group 1644 and the frame AI data1638 corresponding to the frame 1649, based on the synchronization data1631. Then, the AI up-scaler 234 may obtain the up-scaling DNNinformation for AI up-scaling of the low resolution image of the frame1649, considering the video segment AI data 1634 applied to all framestogether with the frame group AI data 1636 and the frame AI data 1638.

According to an embodiment of the disclosure, the AI data 1632 of thesegment metadata box 1630 may be decoded before the video segment data1641 of the segment media data box 1640. Accordingly, the AI up-scaler234 may obtain the up-scaling DNN information before decoding of thevideo segment data 1641, according to the AI data 1632. The obtainedup-scaling DNN information may be applied to entire video segment.Alternatively, for adaptive AI up-scaling of a frame group unit, theup-scaling DNN information may be pre-obtained differently for eachframe group. Alternatively, for adaptive AI up-scaling of a frame unit,the up-scaling DNN information may be pre-obtained differently for eachframe.

According to an embodiment of the disclosure, the AI up-scaler 234 maydecode the AI data 1632 of the segment metadata box 1630 according to adecoding order of the video segment data 1641 of the segment media databox 1640. For example, the AI up-scaler 234 may decode the frame groupAI data 1636 according to a decoding order of the frame group header1646 by the first decoder 232. Also, the AI up-scaler 234 may decode theframe AI data 1638 according to a decoding of the frame header 1648 bythe first decoder 232. A decoding order of the video segment AI data1634, the frame group AI data 1636, and the frame AI data 1638 and adecoding order of the video segment header 1642, the frame group header1646, and the frame header 1648 may be synchronized by referring to thesynchronization data 1631.

Remaining video segment data boxes after the current video segment databox 1620 may be sequentially decoded in the same method as the currentvideo segment data box 1620.

FIG. 17 illustrates an example of AI data 1740 and image data 1700transmitted in two separate files.

When the communicator 212 did not receive the AI data 1740, a lowresolution image obtained from the image data 1700 is not AI up-scaled.When the communicator 212 received the AI data 1740, up-scaling DNNinformation required for AI up-scaling of the low resolution image isobtained according to the AI data 1740 transmitted to the AI up-scaler234 through the outputter 216.

The image data 1700 may include a video header 1710, a frame groupheader 1722 of a frame group 1720, and a frame header 1732 of a frame1730. Also, the AI data 1740 may include video AI data 1742, frame groupAI data 1750, and frame AI data 1760. Because the image data 1700 andthe AI data 1740 are transmitted in separate files, the image data 1700and/or the AI data 1740 may include synchronization data required forsynchronization of the image data 1700 and the AI data 1740. Thesynchronization data may indicate a decoding order or reproduction orderof the image data 1700.

The parser 214 or AI up-scaler 234 may set a reproduction order ordecoding order of the video AI data 1742, the frame group AI data 1750,and the frame AI data 1760 to match a reproduction order or decodingorder of the video header 1710, the frame group header 1722, and theframe header 1732, according to the synchronization data. A dashed arrowbetween the video AI data 1742 and the video header 1710, a dashed arrowbetween the frame group AI data 1750 and the frame group header 1722,and a dashed arrow between the frame AI data 1760 and the frame header1732 of FIG. 17 indicate synchronization between AI data and a dataheader.

The image data 1700 and the AI data 1740 may include identificationnumbers for matching two pieces of data. For example, the AI data 1740may include the identification number of the image data 1700 to whichthe AI data 1740 is applied. On the other hand, the image data 1700 mayinclude the identification number of the AI data 1740 to which the imagedata 1700 is applied. Alternatively, the image data 1700 and the AI data1740 may both include the identification numbers. Accordingly, even whenthe image data 1700 and the AI data 1740 are not simultaneouslytransmitted, the image data 1700 and the AI data 1740 may be matched toeach other according to the identification numbers.

According to an embodiment of the disclosure, when up-scaling DNNinformation is obtained in frame group units, the frame AI data 1760 maybe omitted from the AI data 1740. Also, when the same up-scaling DNNinformation is used for all frames of a video, the frame group AI data1750 and the frame AI data 1760 may be omitted from the AI data 1740.

FIG. 18A illustrates an example of a data structure 1800 applicable tovideo AI data described in FIGS. 14 through 17.

The data structure 1800 of the video AI data includes elements relatedto up-scaling DNN information used for AI up-scaling. The elements mayinclude ai_codec_info 1802, ai_codec_applied_channel_info 1804,target_bitrate_info 1806, res_info 1808, ai_codec_DNN_info 1814, andai_codec_supplementary_info 1816. An arrangement order of the elementsshown in FIG. 18A is only an example and one of ordinary skill in theart may change and execute the arrangement order of the elements.

According to an embodiment of the disclosure, the ai_codec_info 1802denote AI target data indicating whether AI up-scaling is to be appliedto a low resolution image. When the ai_codec_info 1802 indicates that AIup-scaling is applied to a low resolution image reconstructed accordingto image data, the data structure 1800 includes AI supplementary datafor obtaining up-scaling DNN information used for the AI up-scaling. Onthe other hand, when the ai_codec_info 1802 indicates that AI up-scalingis not applied to the low resolution image reconstructed according tothe image data, the data structure 1800 may not include the AIsupplementary data regarding the AI up-scaling. The AI supplementarydata includes the ai_codec_applied_channel_info 1804, the t, theres_info 1808, the ai_codec_DNN_info 1814, and theai_codec_supplementary_info 1816.

The ai_codec_applied_channel_info 1804 is channel information indicatinga color channel to which AI up-scaling is applied. An image may berepresented in an RGB format, a YUV format, or a YCbCr format. When thelow resolution image reconstructed from the image data is in the YCbCrformat, the low resolution image includes a low resolution image of a Ychannel regarding luminance, a low resolution image of a Cb channelregarding chrominance, and a low resolution image of a Cr channel. Theai_codec_applied_channel_info 1804 may indicate a color channel to whichAI up-scaling is applied among three channels. Also, the AI up-scaler234 may AI up-scale a low resolution image of a color channel indicatedby the ai_codec_applied_channel_info 1804. The AI up-scaler 234 mayobtain different pieces of up-scaling DNN information for each colorchannel.

According to an embodiment of the disclosure, AI up-scaling may beapplied only to the low resolution image of the Y channel regardingluminance to reduce throughput according to AI up-scaling. Because humaneyes are more sensitive to image quality with respect to luminancerather than chrominance, a difference in people's subjective sense ofimage quality may be insignificant between when a low resolution imageof all color channels is AI up-scaled and when only a low resolutionimage of a Y channel is AI up-scaled.

Thus, the ai_codec_applied_channel_info 1804 may indicate whether thelow resolution image of the Cb channel and the low resolution image ofthe Cr channel are AI up-scaled. When the ai_codec_applied_channel_info1804 indicates that the low resolution image of the Cb channel and thelow resolution image of the Cr channel are not AI up-scaled, the AIup-scaler 234 may apply AI up-scaling only on the low resolution imageof the Y channel. On the other hands, when theai_codec_applied_channel_info 1804 indicates that the low resolutionimage of the Cb channel and the low resolution image of the Cr channelare AI up-scaled, the AI up-scaler 234 may apply AI up-scaling on thelow resolution images of all channels.

The target_bitrate_info 1806 is information indicating a bitrate of theimage data obtained as a result of the first encoding performed by thefirst encoder 614. The AI up-scaler 234 may obtain up-scaling DNNinformation suitable for image quality of the low resolution image,according to the target_bitrate_info 1806.

The res_info 1808 indicates resolution image related to resolution of ahigh resolution image obtained via AI up-scaling, such as the thirdimage 145. The res_info 1808 may include pic_width_org_luma 1810 andpic_height_org_luma 1812. The pic_width_org_luma 1810 and thepic_height_org_luma 1812 are high resolution image width information andhigh resolution image height information indicating the width and heightof the high resolution image, respectively. The AI up-scaler 234 maydetermine an AI up-scaling rate according to the resolution of the highresolution image determined by the pic_width_org_luma 1810 and thepic_height_org_luma 1812, and the resolution of the low resolution imagereconstructed by the first decoder 232.

According to an embodiment of the disclosure, the res_info 1808 mayinclude resolution ratio information indicating a resolution ratio ofthe low resolution image and the high resolution image, instead of thepic_width_org_luma 1810 and the pic_height_org_luma 1812. Accordingly,the AI up-scaler 234 may determine the resolution of the high resolutionimage according to the resolution ratio according to the resolutionratio information and the resolution of the low resolution imagereconstructed by the first decoder 232. The resolution ratio informationmay include vertical resolution ratio information and horizontalresolution ratio information.

The AI up-scaler 234 may obtain up-scaling DNN information suitable forAI up-scaling of the low resolution image, according to the AIup-scaling rate determined according to the res_info 1808.Alternatively, the AI up-scaler 234 may obtain the up-scaling DNNinformation suitable for AI up-scaling of the low resolution image,according to the resolution of the low resolution image and theresolution of the high resolution image determined according to theres_info 1808.

The ai_codec_DNN_info 1814 is information indicating pre-agreedup-scaling DNN information used for AI up-scaling of the low resolutionimage. The AI up-scaler 234 may determine one of a plurality of piecesof pre-stored default DNN configuration information as the up-scalingDNN information, according to the ai_codec_applied_channel_info 1804,the target_bitrate_info 1806, and the res_info 1808. Also, the AIup-scaler 234 may determine one of the plurality of pieces of pre-storeddefault DNN configuration information as the up-scaling DNN informationadditionally considering other features (a genre, maximum luminance,color gamut of an image, and the like) of the high resolution image.

When there are two or more pieces of default DNN configurationinformation matching a certain condition, the ai_codec_DNN_info 1814 mayindicate one of the two or more pieces of default DNN configurationinformation. Also, the AI up-scaler 234 may AI up-scale the lowresolution image by using up-scaling DNN information indicated by theai_codec_DNN_info 1814.

According to an embodiment of the disclosure, when there are two or morepieces of default DNN configuration information matching a certaincondition, the ai_codec_DNN_info 1814 may indicate two or more pieces ofup-scaling DNN information applicable to a current video file among thetwo or more pieces of default DNN configuration information. Also, oneof the two or more pieces of up-scaling DNN information indicated by theai_codec_DNN_info 1814 may be adaptively selected in frame group orframe units.

The ai_codec_supplementary_info 1816 indicates supplementary informationregarding AI up-scaling. The ai_codec_supplementary_info 1816 mayinclude information required to determine up-scaling DNN informationapplied to a video. The ai_codec_supplementary_info 1816 may includeinformation about a genre, high dynamic range (HDR) maximum luminance,HDR color gamut, HDR perceptual quantizer (PQ), codec, and a ratecontrol type.

The ai_codec_applied_channel_info 1804, the target_bitrate_info 1806,the res_info 1808, the ai_codec_DNN_info 1814, and theai_codec_supplementary_info 1816 of FIG. 18A may be partially omittedaccording to an embodiment of the disclosure. The video AI data havingthe data structure 1800 including the elements may be applied to allframe groups.

FIG. 18B illustrates an example of a data structure 1820 applicable tovideo segment AI data described in FIG. 16 or frame group AI data ofFIGS. 14, 15A to 15C, and 17.

The data structure 1820 has a similar structure as the data structure1800 of FIG. 18A. ai_codec_info 1822, ai_codec_applied_channel_info1826, target_bitrate_info 1828, res_info 1830, pic_width_org_luma 1832,pic_height_org_luma 1834, ai_codec_DNN_info 1836, andai_codec_supplementary_info 1838 of FIG. 18B may perform the samefunctions as the ai_codec_info 1802, the ai_codec_applied_channel_info1804, the target_bitrate_info 1806, the res_info 1808, thepic_width_org_luma 1810, the pic_height_org_luma 1812, theai_codec_DNN_info 1814, and the ai_codec_supplementary_info 1816 of FIG.18A.

However, the data structure 1820 may additionally include AIsupplementary data dependency information (dependent_ai_condition_info1824) indicating whether AI supplementary data is the same between aconsecutive previous data unit and a current data unit. The datastructure 1820 may include the dependent_ai_condition_info 1824 when theai_codec_info 1822 indicates that AI up-scaling is applied to a lowresolution image. When the ai_codec_info 1822 indicates that AIup-scaling is not applied to the low resolution image, thedependent_ai_condition_info 1824 may be omitted from the data structure1820.

When the dependent_ai_condition_info 1824 indicates that the AIsupplementary data is the same between the consecutive previous dataunit and the current data unit, the ai_codec_applied_channel_info 1826,the target_bitrate_info 1828, the res_info 1830, the pic_width_org_luma1832, the pic_height_org_luma 1834, the ai_codec_DNN_info 1836, and theai_codec_supplementary_info 1838 may be omitted from the data structure1820. Also, channel information, target bitrate information, resolutioninformation, DNN information, and supplementary information aredetermined from the ai_codec_applied_channel_info 1826, thetarget_bitrate_info 1828, the res_info 1830, the pic_width_org_luma1832, the pic_height_org_luma 1834, the ai_codec_DNN_info 1836, and theai_codec_supplementary_info 1838 of a previous data unit. Accordingly,when the same AI supplementary data is applied to a plurality of dataunits, the size of AI data may be reduced according to thedependent_ai_condition_info 1824.

When the dependent_ai_condition_info 1824 indicates that the AIsupplementary data is not the same between the consecutive previous dataunit and the current data unit, the data structure 1820 includes theai_codec_applied_channel_info 1826, the target_bitrate_info 1828, theres_info 1830, the pic_width_org_luma 1832, the pic_height_org_luma1834, the ai_codec_DNN_info 1836, and the ai_codec_supplementary_info1838. Also, up-scaling DNN information of the current data unit may beindependently obtained regardless of up-scaling DNN information of theprevious data unit.

According to an embodiment of the disclosure, AI supplementary datadependency information of an initially transmitted data unit may beomitted. Thus, AI supplementary data dependency information is includedin a video segment header from a video segment transmitted second.

According to an embodiment of the disclosure, the AI supplementary datadependency information may indicate only dependency of a certain AIsupplementary data. For example, the AI supplementary data dependencyinformation may indicate whether the current data unit inheritsresolution information of the previous data unit. The AI data inheritedaccording to the AI supplementary data dependency information mayinclude at least one of the ai_codec_info 1822, theai_codec_applied_channel_info 1804, the target_bitrate_info 1806, theres_info 1808, the ai_codec_DNN_info 1814, or theai_codec_supplementary_info 1816.

In FIG. 18B, the data unit may be a video segment or frame group. Whenthe data unit is a video segment, the dependent_ai_condition_info 1824may indicate whether AI supplementary data is the same between aconsecutive previous video segment and a current video segment. When thedata unit is a frame group, the dependent_ai_condition_info 1824 mayindicate whether AI supplementary data is the same between a consecutiveprevious frame group and a current frame group.

FIG. 19 illustrates a syntax table 1900 in which the data structure 1800of FIG. 18A is implemented.

According to the syntax table 1900, syntax elements such asai_codec_info, ai_codec_applied_channel_info, target_bitrate,pic_width_org_luma, pic_height_org_luma, ai_codec_DNN_info, andai_codec_supplementary_info_flag are parsed.

The ai_codec_info is AI target data corresponding to the ai_codec_info1802 of FIG. 18A. When the ai_codec_info indicates that AI up-scaling isallowed (if(ai_codec_info)), syntax elements corresponding to AIsupplementary data are parsed. When the ai_codec_info indicates that AIup-scaling is not allowed, the syntax elements corresponding to the AIsupplementary data are not parsed.

The syntax elements corresponding to the AI supplementary data includeai_codec_applied_channel_info, target_bitrate, pic_width_org_luma,pic_height_org_luma, ai_codec_DNN_info, andai_codec_supplementary_info_flag.

The ai_codec_applied_channel_info corresponds to theai_codec_applied_channel_info 1804 of FIG. 18A. The target_bitrate istarget bitrate information corresponding to the target_bitrate_info 1806of FIG. 18A. The pic_width_org_luma and the pic_height_org_luma are highresolution image width information and high resolution image heightinformation corresponding to pic_width_org_luma 1810 andpic_height_org_luma 1812 of FIG. 18A, respectively. Theai_codec_DNN_info is DNN information corresponding to theai_codec_DNN_info 1814 of FIG. 18A.

The ai_codec_supplementary_info_flag is a supplementary information flagindicating whether the ai_codec_supplementary_info 1816 of FIG. 18A isincluded in the syntax table 1900. When theai_codec_supplementary_info_flag indicates that supplementaryinformation used for AI up-scaling is not parsed, additionalsupplementary information is not obtained. However, when theai_codec_supplementary_info_flag indicates that the supplementaryinformation used for AI up-scaling is parsed(if(ai_codec_supplementary_info_flag)), the additional supplementaryinformation is obtained.

The obtained additional supplementary information may includegenre_info, hdr_max_luminance, hdr_color gamut, hdr_pq_type, andrate_control_type. The genre_info indicates a genre of content of imagedata, the hdr_max_luminance indicates HDR maximum luminance applied to ahigh resolution image, the hdr_color_gamut indicates HDR gamut appliedto the high resolution image, the hdr_pq_type indicates HDR PQinformation applied to the high resolution image, and rate_control_typeindicates a rate control type applied to image data obtained as a resultof first encoding. According to an embodiment of the disclosure, acertain syntax element may be parsed among the syntax elementscorresponding to the supplementary information.

The syntax table 1900 of FIG. 19 is only an example and some of theelements of the data structure 1800 of FIG. 18A may be included in thesyntax table 1900. Also, an element that is not included in the datastructure 1800 may be included in the syntax table 1900.

According to an embodiment of the disclosure, the syntax table 1900 ofFIG. 19 may include AI supplementary data dependency information such asdependent_ai_condition_info, like the data structure 1820 of FIG. 18B.Accordingly, the syntax table 1900 to which the AI supplementary datadependency information is added may be applied to a video segment orframe group.

FIG. 20 illustrates an example of a data structure 2000 applicable to(frame group AI data or) frame AI data described in FIGS. 14 through 17.

Elements for adaptively determining up-scaling DNN information in frameunits are included in the data structure 2000. The elements may includeai_codec_frame_info 2002, dependent_ai_condition_frame_info 2004,ai_codec_frame_DNN_info 2006, ai_codec_enhancement_flag 2008, andai_codec_artifact_removal_flag 2014. An arrangement order of theelements shown in FIG. 20 is only an example and one of ordinary skillin the art may change and execute the arrangement order of the elements.

The ai_codec_frame_info 2002 is frame AI target data indicating whetherAI up-scaling is allowed for a current frame. According to theai_codec_frame_info 2002, when AI up-scaling is allowed for the currentframe, the data structure 2000 includes frame AI supplementary datarelated to AI up-scaling of the current frame. Otherwise, AI up-scalingis not applied to the current frame and the data structure 2000 does notinclude the frame AI supplementary data. The frame AI supplementary datadenotes AI supplementary data applied to a frame.

According to an embodiment of the disclosure, when AI up-scaling isallowed for the current frame according to the ai_codec_frame_info 2002,the data structure 2000 may include thedependent_ai_condition_frame_info 2004. Thedependent_ai_condition_frame_info 2004 is frame AI supplementary datadependency information indicating whether frame AI supplementary data isthe same between a consecutive previous frame and the current frame.When the dependent_ai_condition_frame_info 2004 indicates that the frameAI supplementary data is the same between the consecutive previous frameand the current frame, the data structure 2000 may not includeadditional frame AI supplementary data regarding the current frame, andup-scaling DNN information of the current frame is determined to be thesame as up-scaling DNN information of the previous frame. When thedependent_ai_condition_frame_info 2004 indicates that the frame AIsupplementary data is not the same between the consecutive previousframe and the current frame, the data structure 2000 includes theadditional frame AI supplementary data regarding the current frame, andthe up-scaling DNN information of the current frame is obtainedindependently from the up-scaling DNN information of the previous frame.The additional frame AI supplementary data may include theai_codec_frame_DNN_info 2006, the ai_codec_enhancement_flag 2008, andthe ai_codec_artifact_removal_flag 2014.

The ai_codec_frame_DNN_info 2006 is frame DNN information indicating theup-scaling DNN information of the current frame from among a pluralityof pieces of up-scaling DNN information regarding a higher data unit ofthe current frame. When the ai_codec_DNN_info 1814 of FIG. 18A indicatestwo or more pieces of up-scaling DNN information regarding a video, theai_codec_frame_DNN_info 2006 may determine the up-scaling DNNinformation of the current frame from the two or more pieces ofup-scaling DNN information. Alternatively, when the ai_codec_DNN_info1836 of FIG. 18B indicates two or more pieces of up-scaling DNNinformation regarding a video segment or frame group, theai_codec_frame_DNN_info 2006 may determine the up-scaling DNNinformation of the current frame from the two or more pieces ofup-scaling DNN information. When the ai_codec_DNN_info 1814 of FIG. 18Aor the ai_codec_DNN_info 1836 of FIG. 18B indicates only one piece ofup-scaling DNN information, the ai_codec_frame_DNN_info 2006 may beomitted.

The ai_codec_enhancement_flag 2008 is AI enhancement informationindicating whether an enhancement process of AI up-scaling accuracy isactivated. When the ai_codec_enhancement_flag 2008 indicates that theenhancement process of the AI up-scaling accuracy is activated, some ofsamples of an AI up-scaled high resolution image are adjusted accordingto encoding parameter information. When the ai_codec_enhancement_flag2008 indicates that the enhancement process of the AI up-scalingaccuracy is not activated, the enhancement process is omitted.

An encoding parameter is generated when the original image 105 or thefirst image 115 is encoded at an encoding end. The encoding parametermay be generated according to prediction, transform, and in-loopfiltering process of a data unit (largest coding unit, coding unit,prediction unit, transform unit, or pixel unit). The encoding parameterincludes a motion vector, a prediction motion vector, an intra mode,residual signal-related information, and SAO parameter.

The encoding parameter information is information required for anenhancement process according to the encoding parameter. The encodingparameter information may include encoding parameter type informationindicating a type of an encoding parameter referred to for theenhancement process and encoding parameter map information indicating anapplied region of the enhancement process in the current frame.

When the ai_codec_enhancement_flag 2008 indicates that the enhancementprocess of the AI up-scaling accuracy is activated, the data structure2000 may include encod_param_type 2010 that is the encoding parametertype information and encod_param_map 2012 that is the encoding parametermap information. For example, the encod_param_type 2010 may indicate themotion vector. Also, the encod_param_map 2012 may indicate the appliedregion of the enhancement process according to the motion vector in theAI up-scaled high resolution image. Also, pixels of the applied regionmay be modified according to the motion vector.

According to an embodiment of the disclosure, the encod_param_type 2010may indicate two or more encoding parameters. Also, the encod_param_map2012 may indicate the applied region of the enhancement processregarding each encoding parameter.

According to an embodiment of the disclosure, the encod_param_type 2010and the encod_param_map 2012 may be omitted from the data structure2000. Accordingly, one or more encoding parameters referred to in theenhancement process and the applied region of each encoding parametermay be pre-determined.

The ai_codec_artifact_removal_flag 2014 is artifact removal informationindicating whether artifact removal of an AI up-scaled high resolutionimage is performed. For the artifact removal of the high resolutionimage, pixels of a low resolution image before AI up-scaling may becorrected or pixels of the high resolution image after AI up-scalingaccording to a second DNN may be corrected according to the artifactremoval information, thereby removing artifact.

The artifact removal information may include artifact type informationindicating an artifact type and artifact map information indicating anartifact region where artifact is located. Also, the artifact removalinformation may include artifact type number information indicating thenumber of artifact types of an image. Accordingly, the data structure2000 may include the numbers of pieces of artifact type information andthe artifact map information equal to the number according to theartifact type number information.

The artifact type includes contour artifact, ringing artifact, andaliasing artifact. Also, one or more artifact regions are determined foreach artifact type. For example, one or more artifact regions may bedetermined for contour artifact and one or more artifact regions may bedetermined for ringing artifact.

When the ai_codec_artifact_removal_flag 2014 indicates that artifactremoval of the AI up-scaled high resolution image is performed, the datastructure 2000 may include num_artifact_type 2016 that is the artifacttype number information. When the ai_codec_artifact_removal_flag 2014indicates that artifact removal of the AI up-scaled high resolutionimage is not performed, the num_artifact_type 2016 is omitted from thedata structure 2000.

The data structure 2000 may include artifact_type 2018 that is theartifact type information as much as the number indicated by thenum_artifact_type 2016. Also, the data structure 2000 may include theartifact map information for each artifact_type 2018. The artifact mapinformation of the data structure 2000 may include num_artifact_map 2020indicating the number of artifact regions. Also, the data structure 2000may include map_x_pos 2022, map_y_pos 2024, map_width 2026, map_height2028 indicating a location and size of each artifact region.

According to an embodiment of the disclosure, some of thedependent_ai_condition_frame_info 2004, the ai_codec_frame_DNN_info2006, the ai_codec_enhancement_flag 2008, and theai_codec_artifact_removal_flag 2014 of FIG. 20 may be omitted from thedata structure 2000.

According to an embodiment of the disclosure, the data structure 2000 ofFIG. 20 may be applied to a frame group instead of the frame. When thedata structure 2000 is applied to the frame group, the same up-scalingDNN information, the same AI enhancement information, and the sameartifact removal information may be applied to all frames included inthe frame group. Also, when the data structure 2000 is applied to theframe group, the data structure 2000 may includeai_codec_frame_group_info, dependent_ai_condition_frame_group_info, andai_codec_frame_group_DNN_info applied to the frame group instead of theai_codec_frame_info 2002, the dependent_ai_condition_frame_info 2004,and the ai_codec_frame_DNN_info 2006. Also, theai_codec_enhancement_flag 2008, the encod_param_type 2010, theencod_param_map 2012, the ai_codec_artifact_removal_flag 2014, thenum_artifact_type 2016, the artifact type 2018, the num_artifact_map2020, the map_x_pos 2022, the map_y_pos 2024, the map_width 2026, andthe map_height 2028 may be applied to all frames of the frame group.

According to an embodiment of the disclosure, the data structure 1800 ofFIG. 18A may be applied to video AI data. Also, the data structure 2000of FIG. 20 may be applied to frame AI data. The video AI data accordingto the data structure 1800 includes AI data commonly applied to allframes, and the frame AI data according to the data structure 2000includes AI data adaptively applied to a frame.

According to an embodiment of the disclosure, the data structure 1800 ofFIG. 18A may be applied to video AI data. Also, the data structure 2000of FIG. 20 may be applied to frame group AI data. The video AI dataaccording to the data structure 1800 includes AI data commonly appliedto all frames, and the frame group AI data according to the datastructure 2000 includes AI data adaptively applied to a frame group.Also, the same AI data is applied to all frames included in the framegroup.

According to an embodiment of the disclosure, the data structure 1820 ofFIG. 18B may be applied to video segment AI data or frame group AI data.Also, the data structure 2000 of FIG. 20 may be applied to frame AIdata. The video segment AI data or the frame group AI data according tothe data structure 1820 includes AI data commonly applied to all framesof a video segment or a frame group, and the frame AI data according tothe data structure 2000 includes AI data adaptively applied to a frame.

According to an embodiment of the disclosure, the data structure 1820 ofFIG. 18B may be applied to video segment AI data. Also, the datastructure 2000 of FIG. 20 may be applied to frame group AI data. Thevideo segment AI data according to the data structure 1820 includes AIdata commonly applied to all frames of a video segment, and the framegroup AI data according to the data structure 2000 includes AI dataadaptively applied to a frame group. Also, the same AI data is appliedto all frames included in the frame group.

FIG. 21 illustrates a syntax table 2100 in which the data structure 2000of FIG. 20 is implemented.

According to the syntax table 2100, syntax elements such asai_codec_frame_info, dependent_ai_condition_frame_info,ai_codec_frame_DNN_info, ai_codec_enhancement_flag, andai_codec_artifact_removal_flag are parsed.

The ai_codec_frame_info is frame AI target data corresponding to theai_codec_frame_info 2002 of FIG. 20. When the ai_codec_frame_infoindicates that AI up-scaling is allowed (if(ai_codec_frame_info)),syntax elements corresponding to frame AI supplementary data are parsed.When the ai_codec_frame_info indicates that AI up-scaling is notallowed, the syntax elements corresponding to the frame AI supplementarydata are not parsed.

The syntax elements corresponding to the frame AI supplementary data mayinclude dependent_ai_condition_frame_info, ai_codec_frame_DNN_info,ai_codec_enhancement_flag, and ai_codec_artifact_removal_flag. Thedependent_ai_condition_frame_info, the ai_codec_frame_DNN_info, theai_codec_enhancement_flag, and the ai_codec_artifact_removal_flag ofFIG. 21 correspond to the dependent_ai_condition_frame_info 2004, theai_codec_frame_DNN_info 2006, the ai_codec_enhancement_flag 2008, andthe ai_codec_artifact_removal_flag 2014 of FIG. 20.

When the ai_codec_frame_info indicates that AI up-scaling is allowed,dependent_ai_condition_frame_info is obtained. When thedependent_ai_condition_frame_info indicates that the frame AIsupplementary data is the same between a consecutive previous frame anda current frame, up-scaling DNN information of the current frame isdetermined to be the same as up-scaling DNN information of the previousframe. When the dependent_ai_condition_frame_info indicates that theframe AI supplementary data is not the same between the consecutiveprevious frame and the current frame, up-scaling DNN information, AIenhancement information, and artifact removal information of the currentframe are determined according to ai_codec_frame_DNN_info,ai_codec_enhancement_flag, and ai_codec_artifact_removal_flag.

The ai_codec_frame_DNN_info indicates the up-scaling DNN information ofthe current frame among a plurality of pieces of up-scaling DNNinformation regarding a higher data unit of the current frame.

The ai_codec_enhancement_flag indicates whether an enhancement processof AI up-scaling accuracy is activated. When theai_codec_enhancement_flag indicates that the enhancement process isactivated (if(ai_codec_enhancementilag)), encod_param_type indicating anencoding parameter type and encod_param_map indicating an encodingparameter region are obtained.

The ai_codec_artifact_removal_flag indicates whether artifact removal ofan AI up-scaled high resolution image is performed. When theai_codec_artifact_removal_flag indicates that the artifact removal ofthe high resolution image is performed(if(ai_codec_artifact_removal_flag)), num_artifact_type indicating thenumber of artifact types is obtained. artifact_type indicating anartifact type and num_artifact_map indicating the number of artifactregions are obtained as much as the number indicated by thenum_artifact_type (for(i=0; i<num_artifact_type, i++)). Also, map_x_pos,map_y_pos, map_width, and map_height indicating a location and size ofan artifact region are obtained as much as the number ofnum_artifact_map (for(i=0; i<num_artifact_map, i++)).

The syntax table 2100 of FIG. 21 is only an example and some of elementsof the data structure 2000 of FIG. 20 may be included in the syntaxtable 2100. Also, an element not included in the data structure 2000 maybe included in the syntax table 2100.

FIG. 22 is a flowchart of an image decoding method according to an AIdecoder, according to an embodiment of the disclosure.

In operation 2210, a video file including AI encoding data includingimage data and AI data about AI up-scaling of the image data isreceived. The receiving of the AI encoding data in operation 2210 may beperformed by the communicator 212.

In operation 2220, the AI data of the AI encoding data is obtained froma metadata box of the video file and the image data of the AI encodingdata is obtained from a media data box of the video file. When the imagedata and the AI data are separated, the obtaining of the image data andthe AI data in operation 2220 may be performed by the parser 214.Alternatively, when the AI data is included in the image data, the AIdata may be obtained from the image data by the first decoder 232.

According to an embodiment of the disclosure, the AI encoding data mayinclude synchronization data about synchronization of the image data andthe AI data. The synchronization data may indicate a relationshipbetween the image data and the AI data according to a decoding order orreproduction order of the image data. The synchronization data mayinclude information about synchronization of a video header and video AIdata, synchronization of a frame group header and frame group AI data,and synchronization of a frame header and frame AI data.

In operation 2230, a low resolution image of a current frame isreconstructed by decoding the image data. The reconstructing of the lowresolution image according to operation 2230 may be performed by thefirst decoder 232.

In operation 2240, up-scaling DNN information of the current frame isobtained from the AI data. The obtaining of the up-scaling DNNinformation of the current frame according to operation 2240 may beperformed by the AI up-scaler 234.

According to an embodiment of the disclosure, the AI data may includevideo AI data, frame group AI data, and frame AI data according to alayer structure of the AI data of FIG. 12. In addition, the AI data mayinclude video segment AI data of FIG. 16. The AI data according to thelayer structure may include up-scaling DNN information applied to acorresponding layer.

According to an embodiment of the disclosure, the AI data may includethe video AI data. When only the video AI data is included in the AIdata, up-scaling DNN information applied to all frames of the image datamay be obtained from a plurality of pieces of default DNN configurationinformation according to the video AI data.

According to an embodiment of the disclosure, the AI data may includethe frame group AI data. When only the frame group AI data is includedin the AI data, up-scaling DNN information applied to all frames of theframe group may be obtained adaptively to the frame group from aplurality of pieces of default DNN configuration information accordingto the frame group AI data.

According to an embodiment of the disclosure, the AI data may includethe frame AI data. When only the frame AI data is included in the AIdata, up-scaling DNN information applied to the frame may be obtainedadaptively to the frame from a plurality of pieces of default DNNconfiguration information according to the frame AI data.

According to an embodiment of the disclosure, the AI data may includethe frame group AI data together with the video AI data. When only thevideo AI data and the frame group AI data are included in the AI data,one or more pieces of up-scaling DNN information may be obtained from aplurality of pieces of default DNN configuration information accordingto the video AI data. Also, up-scaling DNN information applied to framesof the frame group may be selected from the one or more pieces ofup-scaling DNN information according to the frame group AI data.

According to an embodiment of the disclosure, the AI data may includethe frame AI data together with the video AI data. When only the videoAI data and the frame AI data are included in the AI data, one or morepieces of up-scaling DNN information may be obtained from a plurality ofpieces of default DNN configuration information according to the videoAI data. Also, up-scaling DNN information applied to the frame may beselected from the one or more pieces of up-scaling DNN informationaccording to the frame AI data.

According to an embodiment of the disclosure, the AI data may includethe frame AI data together with the frame group AI data. When only theframe group AI data and the frame AI data are included in the AI data,one or more pieces of up-scaling DNN information may be obtained from aplurality of pieces of default DNN configuration information accordingto the frame group AI data. Also, up-scaling DNN information applied tothe frame may be selected from the one or more pieces of up-scaling DNNinformation according to the frame AI data.

According to an embodiment of the disclosure, the AI data may includethe video segment AI data. When only the video segment AI data isincluded in the AI data, up-scaling DNN information applied to allframes of the video segment may be obtained from a plurality of piecesof default DNN configuration information according to the video segmentAI data.

According to an embodiment of the disclosure, the AI data may includethe video AI data together with the video segment AI data. When only thevideo AI data and the video segment AI data are included in the AI data,one or more pieces of up-scaling DNN information may be obtained from aplurality of pieces of default DNN configuration information accordingto the video AI data. Also, up-scaling DNN information applied to allframes of the video segment may be selected from the one or more piecesof up-scaling DNN information according to the video segment AI data.

According to an embodiment of the disclosure, the AI data may includethe frame group AI data or the frame AI data together with the videosegment AI data. When the frame group AI data or the frame AI data isincluded in the AI data together with the video segment AI data, one ormore pieces of up-scaling DNN information may be obtained from aplurality of pieces of default DNN configuration information accordingto the video segment AI data. Also, up-scaling DNN information appliedto the frame group or the frame may be selected from the one or morepieces of up-scaling DNN information according to the frame group AIdata or the frame AI data.

According to an embodiment of the disclosure, the AI data may includeall of the video AI data, the video segment AI data, the frame group AIdata, and the frame AI data. When the AI data includes all of the videoAI data, the video segment AI data, the frame group AI data, and theframe AI data, one or more pieces of up-scaling DNN informationapplicable to a video may be limited from a plurality of pieces ofdefault DNN configuration information according to the video AI data.Also, one or more pieces of up-scaling DNN information applicable to thevideo segment may be selected from the one or more pieces of up-scalingDNN information applicable to the video, according to the video segmentAI data. Also, one or more pieces of up-scaling DNN informationapplicable to the frame group may be selected from the one or morepieces of up-scaling DNN information applicable to the video segment,according to the frame group AI data. Also, up-scaling DNN informationapplied to the frame may be selected from the one or more pieces ofup-scaling DNN information applicable to the frame group, according tothe frame AI data. According to the above embodiment of the disclosure,some of the video AI data, the video segment AI data, the frame group AIdata, and the frame AI data may be excluded from a hierarchical AI datastructure described above.

According to an embodiment of the disclosure, the AI data may include AItarget data indicating whether AI up-scaling is to be applied, and whenthe AI up-scaling is applied, AI supplementary data about up-scaling DNNinformation used in the AI up-scaling.

The video AI data may include video AI target data indicating whether AIup-scaling is to be applied to the image data and video AI supplementarydata about one or more pieces of up-scaling DNN information applicableto AI up-scaling of frames included in the image data. When the video AItarget data indicates that AI up-scaling is applied to the framesincluded in the image data, one or more pieces of up-scaling DNNinformation are obtained according to the video AI supplementary data.

The video segment AI data may include video segment AI target dataindicating whether AI up-scaling is to be applied to the video segmentand video segment AI supplementary data about one or more pieces ofup-scaling DNN information applicable to AI up-scaling of framesincluded in the video segment. When the video segment AI target dataindicates that AI up-scaling is applied to the frames included in thevideo segment, one or more pieces of up-scaling DNN information of thevideo segment are obtained according to the video segment AIsupplementary data.

The frame group AI data may include frame group AI target dataindicating whether AI up-scaling is to be applied to the frame group andframe group AI supplementary data about one or more pieces of up-scalingDNN information applicable to AI up-scaling of frames included in theframe group. When the frame group AI target data indicates that AIup-scaling is applied to the frames included in the frame group, one ormore pieces of up-scaling DNN information of the frame group areobtained according to the frame group AI supplementary data.

The frame AI data may include frame AI target data indicating whether AIup-scaling is to be applied to the frame and frame AI supplementary dataabout up-scaling DNN information used for AI up-scaling of the frame.When the frame AI target data indicates that AI up-scaling is applied tothe current frame, up-scaling DNN information of the current frame isobtained according to the frame AI supplementary data.

According to an embodiment of the disclosure, the video segment AI datamay include video segment AI supplementary data dependency informationindicating whether video segment AI supplementary data is the samebetween a consecutive previous video segment and the current videosegment. When the video segment AI supplementary data dependencyinformation indicates that the video segment AI supplementary data isthe same between the consecutive previous video segment and the currentvideo segment, the video segment AI supplementary data of the currentvideo segment is determined to be the same as the video segment AIsupplementary data of the previous video segment.

Also, the frame group AI data may include frame group AI supplementarydata dependency information indicating whether frame group AIsupplementary data is the same between a consecutive previous framegroup and the current frame group. When the frame group AI supplementarydata dependency information indicates that the frame group AIsupplementary data is the same between the consecutive previous framegroup and the current frame group, the frame group AI supplementary dataof the current frame group is determined to be the same as the framegroup AI supplementary data of the previous frame group.

Also, the frame AI data may include frame AI supplementary datadependency information indicating whether frame AI supplementary data isthe same between a consecutive previous frame and the current frame.When the frame AI supplementary data dependency information indicatesthat the frame AI supplementary data is the same between the consecutiveprevious frame and the current frame, the frame AI supplementary data ofthe current frame may be determined to be the same as the frame AIsupplementary data of the previous frame.

According to an embodiment of the disclosure, the video AI data appliedto the entire image data, the video segment AI data corresponding to thevideo segment, the frame group AI data applied to the frame group, andthe frame AI data applied to the frame may be determined according tosynchronization data.

According to an embodiment of the disclosure, the AI data may includechannel information indicating a color channel to which AI up-scaling isapplied. Also, up-scaling DNN information may be obtained for the colorchannel indicated by the channel information.

According to an embodiment of the disclosure, the AI data may include atleast one of target bitrate information indicating a bitrate of the lowresolution image according to the image data or resolution informationrelated to resolution of an AI up-scaled high resolution image. Also,two or more pieces of up-scaling DNN information regarding the video,the video segment, or the frame group may be determined according to atleast one of the target bitrate information or the resolutioninformation. Also, up-scaling DNN information of the current frame maybe determined from the two or more pieces of up-scaling DNN information,according to the frame AI data.

In operation 2250, a high resolution image corresponding to the lowresolution image is generated by AI up-scaling the low resolution imageaccording to the up-scaling DNN information of the current frame. Thegenerating of the high resolution image according to operation 2250 maybe performed by the AI up-scaler 234.

According to an embodiment of the disclosure, accuracy of the generatedhigh resolution image may be enhanced according to an AI up-scalingenhancement process according to the encoding parameter. Alternatively,artifact of the generated high resolution image may be removed accordingto an artifact removal process.

Functions of the AI up-scaling described with reference to FIGS. 12through 21 may be applied to the image decoding method of FIG. 22.

FIG. 23 is a flowchart of an image encoding method according to an AIencoder, according to an embodiment of the disclosure.

In operation 2310, down-scaling DNN information for AI down-scaling ahigh resolution image of a current frame to a low resolution image isdetermined. The determining of the AI data according to operation 2310may be performed by the AI down-scaler 612.

Two or more pieces of down-scaling DNN information may be determined fora video, a video segment, or a frame group, according to at least one oftarget bitrate information or resolution information. Also, thedown-scaling DNN information of the current frame may be determined fromthe two or more pieces of down-scaling DNN information, according toframe AI data.

In operation 2320, the low resolution image of the current frame isgenerated by AI down-scaling the high resolution image of the currentframe, by using the down-scaling DNN information. The generating of thelow resolution image according to operation 2320 may be performed by theAI down-scaler 612.

In operation 2330, AI data used for AI up-scaling of the low resolutionimage of the current frame is generated. The generating of the lowresolution image according to operation 2330 may be performed by the AIdown-scaler 612. The AI data used for AI up-scaling may be generated byreferring to the down-scaling DNN information generated in operation2310.

According to an embodiment of the disclosure, the AI data may includevideo AI data, frame group AI data, and frame AI data according to alayer structure of the AI data of FIG. 12. In addition, the AI data mayinclude video segment AI data of FIG. 16. The AI data according to thelayer structure may include up-scaling DNN information applied to acorresponding layer.

According to an embodiment of the disclosure, the AI data may includethe video AI data. When only the video AI data is included in the AIdata, the video AI data may indicate up-scaling DNN information appliedto all frames of the image data from a plurality of pieces of defaultDNN configuration information.

According to an embodiment of the disclosure, the AI data may includethe frame group AI data. When only the frame group AI data is includedin the AI data, the frame group AI data may indicate up-scaling DNNinformation applied to all frames of the frame group from a plurality ofpieces of default DNN configuration information.

According to an embodiment of the disclosure, the AI data may includethe frame AI data. When only the frame AI data is included in the AIdata, the frame AI data may indicate up-scaling DNN information appliedto a frame from a plurality of pieces of default DNN configurationinformation.

According to an embodiment of the disclosure, the AI data may includethe frame group AI data together with the video AI data. When only thevideo AI data and the frame group AI data are included in the AI data,the video AI data may include one or more pieces of up-scaling DNNinformation from a plurality of pieces of default DNN configurationinformation. Also, up-scaling DNN information applied to frames of theframe group may be indicated from the one or more pieces of up-scalingDNN information according to the frame group AI data.

According to an embodiment of the disclosure, the AI data may includethe frame AI data together with the video AI data. When only the videoAI data and the frame AI data are included in the AI data, the video AIdata may include one or more pieces of up-scaling DNN information from aplurality of pieces of default DNN configuration information. Also, theframe AI data may indicate up-scaling DNN information applied to theframe from the one or more pieces of up-scaling DNN information.

According to an embodiment of the disclosure, the AI data may includethe frame AI data together with the frame group AI data. When only theframe group AI data and the frame AI data are included in the AI data,the frame group AI data may indicate one or more pieces of up-scalingDNN information from a plurality of pieces of default DNN configurationinformation. Also, the frame AI data may indicate up-scaling DNNinformation applied to the frame from the one or more pieces ofup-scaling DNN information.

According to an embodiment of the disclosure, the AI data may includethe video segment AI data. When only the video segment AI data isincluded in the AI data, the video segment AI data may indicateup-scaling DNN information applied to all frames of the video segmentfrom a plurality of pieces of default DNN configuration information.

According to an embodiment of the disclosure, the AI data may includethe video AI data together with the video segment AI data. When only thevideo AI data and the video segment AI data are included in the AI data,the video AI data may include one or more pieces of up-scaling DNNinformation from a plurality of pieces of default DNN configurationinformation. Also, the video segment AI data may indicate up-scaling DNNinformation applied to all frames of the video segment from the one ormore pieces of up-scaling DNN information.

According to an embodiment of the disclosure, the AI data may includethe frame group AI data or the frame AI data together with the videosegment AI data. When the frame group AI data or the frame AI data isincluded in the AI data together with the video segment AI data, thevideo segment AI data may indicate one or more pieces of up-scaling DNNinformation from a plurality of pieces of default DNN configurationinformation. Also, the frame group AI data or the frame AI data mayindicate up-scaling DNN information applied to the frame group or theframe from the one or more pieces of up-scaling DNN information.

According to an embodiment of the disclosure, the AI data may includeall of the video AI data, the video segment AI data, the frame group AIdata, and the frame AI data. When the AI data includes all of the videoAI data, the video segment AI data, the frame group AI data, and theframe AI data, the video AI data may indicate one or more pieces ofup-scaling DNN information applicable to a video from a plurality ofpieces of default DNN configuration information. Also, the video segmentAI data may indicate one or more pieces of up-scaling DNN informationapplicable to the video segment from the one or more pieces ofup-scaling DNN information applicable to the video. Also, the framegroup AI data may indicate one or more pieces of up-scaling DNNinformation applicable to the frame group from the one or more pieces ofup-scaling DNN information applicable to the video segment. Also, theframe AI data may indicate up-scaling DNN information applied to theframe from the one or more pieces of up-scaling DNN informationapplicable to the frame group. According to the above embodiment of thedisclosure, one of the video AI data, the video segment AI data, theframe group AI data, and the frame AI data may be excluded from ahierarchical AI data structure described above.

According to an embodiment of the disclosure, the AI data may include AItarget data indicating whether AI up-scaling is to be applied. Also,when AI up-scaling is applied, the AI data may include AI supplementarydata about up-scaling DNN information corresponding to the down-scalingDNN information used for AI down-scaling.

The video AI data may include video AI target data indicating whether AIup-scaling is to be applied to the image data and video AI supplementarydata about one or more pieces of up-scaling DNN information applicableto AI up-scaling of frames included in the image data. The video AItarget data may be determined based on whether AI up-scaling is to beapplied to the image data. Also, the video AI supplementary data may bedetermined according to one or more pieces of up-scaling DNN informationof frames included in the image data.

The video segment AI data may include video segment AI target dataindicating whether AI up-scaling is to be applied to the video segmentand video segment AI supplementary data about one or more pieces ofup-scaling DNN information applicable to AI up-scaling of framesincluded in the video segment. The video segment AI target data may bedetermined based on whether AI up-scaling is to be applied to the videosegment. The video segment AI supplementary data may be determinedaccording to one or more pieces of up-scaling DNN information of framesincluded in the video segment.

The frame group AI data may include frame group AI target dataindicating whether AI up-scaling is to be applied to the frame group andframe group AI supplementary data about one or more pieces of up-scalingDNN information applicable to AI up-scaling of frames included in theframe group. The frame group AI target data may be determined based onwhether AI up-scaling is to be applied to the frame group. Also, theframe group AI supplementary data may be determined according to one ormore pieces of up-scaling DNN information applicable to AI up-scaling offrames included in the frame group.

The frame AI data may include frame AI target data indicating whether AIup-scaling is to be applied to the frame and frame AI supplementary dataabout up-scaling DNN information used for AI up-scaling of the frame.

The frame AI target data may be determined based on whether AIup-scaling is to be applied to the current frame. The frame AIsupplementary data may be determined according to up-scaling DNNinformation used for AI up-scaling of the current frame.

According to an embodiment of the disclosure, the video segment AI datamay include video segment AI supplementary data dependency informationindicating whether video segment AI supplementary data is the samebetween a consecutive previous video segment and the current videosegment. The video segment AI supplementary data dependency informationis determined based on whether video segment AI supplementary data issame between a consecutive previous video segment and the current videosegment.

Also, the frame group AI data may include frame group AI supplementarydata dependency information indicating whether frame group AIsupplementary data is the same between a consecutive previous framegroup and the current frame group. The frame group AI supplementary datadependency information is determined based on whether frame group AIsupplementary data is same between a consecutive previous frame groupand the current frame group.

Also, the frame AI data may include frame AI supplementary datadependency information indicating whether frame AI supplementary data isthe same between a consecutive previous frame and the current frame. Theframe AI supplementary data dependency information is determined basedon whether frame AI supplementary data is same between a consecutiveprevious frame and the current frame.

According to an embodiment of the disclosure, AI encoding data mayinclude synchronization data about synchronization of the image data andthe AI data. The synchronization data may include data regardingsynchronization of the image data and the video AI data, synchronizationof the video segment and the video segment AI data, synchronization ofthe frame group and the frame group AI data, and synchronization of thecurrent frame and the frame AI data.

According to an embodiment of the disclosure, the AI data may includechannel information indicating a color channel applied to AI up-scalingof the current frame. Also, up-scaling DNN information may be determinedfor the color channel indicated by the channel information.

According to an embodiment of the disclosure, the AI data may include atleast one of target bitrate information indicating a bitrate of the lowresolution image or resolution information indicating resolution of thehigh resolution image.

In operation 2340, image data is obtained by encoding the low resolutionimage of the current frame. The obtaining of the image data according tooperation 2340 may be performed by the first encoder 614.

In operation 2350, AI encoding data including the image data and the AIdata is generated. The generating of the AI encoding data according tooperation 2350 may be performed by the data processor 632. According toan embodiment of the disclosure, the image data and the AI data may notbe included in a single file but may be configured as separate files.

In operation 2360, a video file including a media data box in which theimage data of the generated AI encoding data is embedded and a metadatabox in which the AI data of the AI encoding data is embedded is output.The outputting of the AI encoding data according to operation 2360 maybe performed by the communicator 634.

Functions of the AI down-scaling corresponding to the AI up-scalingdescribed with reference to FIGS. 12 through 21 may be applied to theimage encoding method of FIG. 23.

FIG. 24 is a block diagram showing a configuration of an image decodingapparatus, according to an embodiment of the disclosure.

Referring to FIG. 24, an image decoding apparatus 2400 according to anembodiment of the disclosure may include a communicator 2410, aprocessor 2420, and a memory 2430.

The communicator 2410 may receive AI encoding data. Alternatively, thecommunicator 2410 may receive AI data and image data from an externaldevice (for example, a server) according to control of the processor2420.

The processor 2420 may control the image decoding apparatus 2400 ingeneral. The processor 2420 according to an embodiment of the disclosuremay execute one or more programs stored in the memory 2430. Theprocessor 2420 may perform functions of the first decoder 232 and the AIup-scaler 234. The processor 2420 may be configured as one or moregeneral-purpose processors.

According to an embodiment of the disclosure, the processor 2420 mayinclude a graphic processor 2422 and an AI-dedicated processor 2424.Also, the processor 2420 may be implemented in a form of a system onchip (SoC) in which at least one of the graphic processor 2422 or theAI-dedicated processor 2424 is integrated. The processor 2420 controlsoverall operations of the image decoding apparatus 2400 and a signalflow between internal components of the image decoding apparatus 2400,and processes data.

The graphic processor 2422 is a processor designed specifically fordecoding and post-processing of an image. Accordingly, the graphicprocessor 2422 may process the image data received by the image decodingapparatus 2400 and efficiently perform a low resolution imagereconstruction function of the first decoder 232. The AI-dedicatedprocessor 2424 is a processor designed specifically for AI operation.Accordingly, the AI-dedicated processor 2424 may efficiently perform alow resolution image AI up-scaling function of the AI up-scaler 234.

The image data and the AI data input to the image decoding apparatus2400 through the communicator 2410 are processed by the processor 2420.A low resolution image may be generated when operations regardingdecoding of the image data are performed by the graphic processor 2422.Also, operations regarding AI up-scaling of the low resolution image maybe performed by the AI-dedicated processor 2424. Thus, a high resolutionimage may be generated as the low resolution image is AI up-scaled bythe AI-dedicated processor 2424.

The processor 2420 is described to include one graphic processor 2422,but may include one or more graphic processors 2422, according to anembodiment of the disclosure. Also, the processor 2420 is described toinclude one AI-dedicated processor 2424, but may include one or moreAI-dedicated processors 2424, according to an embodiment of thedisclosure. Also, the processor 2420 may include one or moregeneral-purpose processors. Additional processes required for AIup-scaling may be performed according to the one or more general-purposeprocessors. The AI-dedicated processor 2424 may be implemented as ahardware field-programmable gate array (FPGA).

The memory 2430 according to an embodiment of the disclosure may includevarious types of data, programs, or applications for driving andcontrolling the image decoding apparatus 2400. The program stored in thememory 2430 may include one or more instructions. Also, the program (oneor more instructions) or application stored in the memory 2430 may beexecuted by the processor 2420. The memory 2430 may store dataoriginated from the communicator 2410 and the processor 2420. Also, thememory 2430 may transmit data required by the processor 2420 to theprocessor 2420.

The image decoding apparatus 2400 according to an embodiment of thedisclosure may perform at least one of functions of the AI decodingapparatus 200 described in FIG. 2 or operations of the image decodingmethod described in FIG. 22.

FIG. 25 is a block diagram showing a configuration of an image encodingapparatus, according to an embodiment of the disclosure.

Referring to FIG. 25, an image encoding apparatus 2500 according to anembodiment of the disclosure may include a communicator 2510, aprocessor 2520, and a memory 2530.

The processor 2520 according to an embodiment of the disclosure maycontrol the image encoding apparatus 2500 in general. The processor 2520according to an embodiment of the disclosure may execute one or moreprograms stored in the memory 2530. The processor 2520 may performfunctions of the AI down-scaler 612 and the first encoder 614. Theprocessor 2520 may be configured as one or more general-purposeprocessors.

According to an embodiment of the disclosure, the processor 2520 mayinclude a graphic processor 2522 and an AI-dedicated processor 2524.Also, the processor 2520 may be implemented in a form of an SoC in whichat least one of the graphic processor 2522 or the AI-dedicated processor2524 is integrated. The processor 2520 controls overall operations ofthe image encoding apparatus 2500 and a signal flow between internalcomponents of the image encoding apparatus 2500, and processes data.

The graphic processor 2522 is a processor designed specifically forencoding and post-processing of an image. Accordingly, the graphicprocessor 2522 may efficiently perform a low resolution image encodingfunction of the first encoder 614. The AI-dedicated processor 2524 is aprocessor designed specifically for AI operation. Accordingly, theAI-dedicated processor 2524 may efficiently perform a high resolutionimage AI down-scaling function of the AI down-scaler 612. TheAI-dedicated processor 2524 may be implemented as a hardware FPGA.

AI down-scaling of the high resolution image and encoding of the lowresolution image are performed by the processor 2520. The low resolutionimage may be generated when operations for AI down-scaling of the highresolution image are performed by the AI-dedicated processor 2524, andAI data required for AI up-scaling of the low resolution image may begenerated by the AI-dedicated processor 2524. Image data may begenerated when operations for encoding the low resolution image areperformed by the graphic processor 2522.

The communicator 2510 may generate a single file of AI encoding dataincluding the AI data and the image data, according to control of theprocessor 2520. Also, the communicator 2510 may output the single fileof the AI encoding data to the outside of the image encoding apparatus2500, according to control of the processor 2520. Alternatively, thecommunicator 2510 may generate a file including the AI data and a fileincluding the image data separately, according to control of theprocessor 2520. Also, the communicator 2510 may output each of the fileincluding the AI data and the file including the image data to theoutside of the image encoding apparatus 2500, according to control ofthe processor 2520.

The processor 2520 is described to include one graphic processor 2522,but may include one or more graphic processors 2522, according to anembodiment of the disclosure. Also, the processor 2520 is described toinclude one AI-dedicated processor 2524, but may include one or moreAI-dedicated processors 2524, according to an embodiment of thedisclosure. Also, the processor 2520 may include one or moregeneral-purpose processors. Additional processes required for AIup-scaling may be performed according to the one or more general-purposeprocessors.

The memory 2530 according to an embodiment of the disclosure may includevarious types of data, programs, or applications for driving andcontrolling the image encoding apparatus 2500. The program stored in thememory 2530 may include one or more instructions. Also, the program (oneor more instructions) or application stored in the memory 2530 may beexecuted by the processor 2520. The memory 2530 may store the highresolution image such as the original image 105. The memory 2530 maystore data originated from the communicator 2510 and the processor 2520.Also, the memory 2530 may transmit data required by the processor 2520to the processor 2520.

The image encoding apparatus 2500 according to an embodiment of thedisclosure may perform at least one of functions of the AI encodingapparatus 600 described in FIG. 7 or operations of the image encodingmethod described in FIG. 23.

Meanwhile, the embodiments of the disclosure described above may bewritten as computer-executable programs or instructions that may bestored in a medium.

The medium may continuously store the computer-executable programs orinstructions, or temporarily store the computer-executable programs orinstructions for execution or downloading. Also, the medium may be anyone of various recording media or storage media in which a single pieceor plurality of pieces of hardware are combined, and the medium is notlimited to a medium directly connected to a computer system, but may bedistributed on a network. Examples of the medium include magnetic media,such as a hard disk, a floppy disk, and a magnetic tape, opticalrecording media, such as CD-ROM and DVD, magneto-optical media such as afloptical disk, and ROM, RAM, and a flash memory, which are configuredto store program instructions. Other examples of the medium includerecording media and storage media managed by application storesdistributing applications or by websites, servers, and the likesupplying or distributing other various types of software.

Meanwhile, a model related to the DNN described above may be implementedvia a software module. When the DNN model is implemented via a softwaremodule (for example, a program module including instructions), the DNNmodel may be stored in a computer-readable recording medium.

Also, the DNN model may be a part of the AI decoding apparatus 200 or AIencoding apparatus 600 described above by being integrated in a form ofa hardware chip. For example, the DNN model may be manufactured in aform of an dedicated hardware chip for AI, or may be manufactured as apart of an existing general-purpose processor (for example, CPU orapplication processor) or a graphic-dedicated processor (for exampleGPU).

Also, the DNN model may be provided in a form of downloadable software.A computer program product may include a product (for example, adownloadable application) in a form of a software program electronicallydistributed through a manufacturer or an electronic market. Forelectronic distribution, at least a part of the software program may bestored in a storage medium or may be temporarily generated. In thiscase, the storage medium may be a server of the manufacturer orelectronic market, or a storage medium of a relay server.

While one or more embodiments of the disclosure have been described withreference to the figures, it will be understood by those of ordinaryskill in the art that various changes in form and details may be madetherein without departing from the spirit and scope as defined by thefollowing claims.

The invention claimed is:
 1. A method for providing an image by a serverconfigured to use artificial intelligence (AI), the method comprising:selecting a down-scaling deep neural network (DNN) setting informationfrom among a plurality of down-scaling DNN setting informationpre-stored at the server for AI down-scaling an original image of atleast one frame; obtaining a down-scaled image of the at least one frameby performing the AI down-scaling of the original image of the at leastone frame, according to the selected down-scaling DNN settinginformation; obtaining AI data about up-scaling DNN setting informationcorresponding to the down-scaling DNN setting information, wherein theup-scaling DNN setting information is used for performing AI up-scalingof the at least one frame through an up-scaling DNN selected from amonga plurality of up-scaling DNNs related to a plurality of up-scaling DNNsetting information that are pre-stored, when the AI up-scaling isperformed on the at least one frame; obtaining image data by encodingthe down-scaled image of the at least one frame; obtaining AI encodingdata including the image data and the AI data; and obtaining a videofile including a media data box in which the image data of the AIencoding data is embedded and a metadata box in which the AI data of theAI encoding data is embedded.
 2. The method of claim 1, wherein the AIdata is frame AI data about AI up-scaling of the at least one frame,frame group AI data about AI up-scaling of a frame group including theat least one frame, video segment AI data about AI up-scaling of a videosegment including the at least one frame, or video AI data about AIup-scaling of a video including the at least one frame.
 3. The method ofclaim 1, wherein: the AI data comprises: at least one AI target dataindicating whether the AI up-scaling is to be performed on the at leastone frame; and at least one AI supplementary data about the up-scalingDNN setting information used to AI up-scale the at least one frame whenthe AI up-scaling is performed on the at least one frame, and theobtaining of the AI data comprises: identifying the at least one AItarget data based on whether the AI up-scaling is to be performed on theat least one frame; and identifying the at least one AI supplementarydata according to the up-scaling DNN setting information of the at leastone frame on which the AI up-scaling is to be performed.
 4. The methodof claim 3, wherein the at least one AI target data includes informationindicating whether the AI up-scaling is to be performed on the at leastone frame or the AI up-scaling is not to be performed on the at leastone frame, the obtaining of the AI data comprises: identifying whetherthe AI up-scaling is to be performed on the at least one frame or not;obtaining the at least one AI target data which includes the informationindicating the AI up-scaling is to be performed on the at least oneframe when the AI up-scaling is to be performed on the at least oneframe; and obtaining the at least one AI target data which includes theinformation indicating the AI up-scaling is not to be performed on theat least one frame when the AI up-scaling is not to be performed on theat least one frame.
 5. The method of claim 1, wherein: the AI datacomprises at least one of target bitrate information indicating abitrate of the down-scaled image or resolution information related toresolution of the original image, and the obtaining of the AI datacomprises identifying two or more pieces of the up-scaling DNN settinginformation of the at least one frame from a plurality of pieces ofdefault DNN setting information, based on at least one of the targetbitrate information or the resolution information.
 6. The method ofclaim 5, wherein the resolution information indicates the resolution ofthe original image.
 7. The method of claim 1, wherein: the metadata boxof the video file comprises synchronization data about synchronizationof the AI data and the image data, and the obtaining of the AI datacomprises identifying the synchronization data according to an encodingorder or reproduction order of the image data and the AI data.
 8. Themethod of claim 1, wherein the encoded image data comprises: video AIdata about the AI up-scaling of the image data; and a video encodingparameter applied to all of a plurality of frames of the image data. 9.A server for providing an image by using artificial intelligence (AI),the server comprising: one or more processors configured to execute oneor more instructions stored in the server to: select a down-scaling deepneural network (DNN) setting information among a plurality ofdown-scaling DNN setting information pre-stored in the server for AIdown-scaling an original image of at least one frame, obtain adown-scaled image of the at least one frame by performing the AIdown-scaling of the original image of the at least one frame, and obtainAI data about up-scaling DNN setting information corresponding to thedown-scaling DNN setting information, wherein the up-scaling DNN settinginformation is used for performing AI up-scaling of the at least oneframe through an up-scaling DNN selected from among a plurality ofup-scaling DNNs related to a plurality of up-scaling DNN settinginformation that are pre-stored, when the AI up-scaling is performed onthe at least one frame, to obtain image data by encoding the down-scaledimage of the at least one frame, to obtain AI encoding data includingthe image data and the AI data, and to obtain a video file including amedia data box in which the image data of the AI encoding data isembedded and a metadata box in which the AI data of the AI encoding datais embedded.